START-INFO-DIR-ENTRY
* mysql: (mysql).               *MySQL* documentation.
END-INFO-DIR-ENTRY

This is a manual for *MySQL*. This
version is about the 3.21.33 version of *MySQL*. For a *3.20* version
see the relevant distribution.

General Information about *MySQL*
*********************************

   This is the *MySQL* reference manual. This version documents the
3.21.33 version of *MySQL*.

   *MySQL* is a basically free, very fast SQL database server. *Note
Licensing and Support::.

   The latest information about *MySQL* is found at the *MySQL* Home page (http://www.tcx.se).

   To see what it can do, *note Features::..

   For installation instructions, *note Installing::.. For tips on how
to port *MySQL* to new machines/operating systems, *note Porting::..

   If you have any suggestions concerning additions to or corrections
to this manual, please send them to the *MySQL* mailing list
<mysql@tcx.se> with the following subject line; `documentation
suggestion: [Insert Topic Here]'.  *Note Mailing-list::.

   *Note Upgrading-from-3.20::, for information about upgrading from a
3.20 release.

   For examples of SQL and benchmarking information, see the `bench'
directory.

   For future plans, *note Todo::..

   For a history of new features/bug fixes, *note News::..

   For the currently known bugs/misfeatures (known errors), *note
Bugs::..

   For A list of all the contributors to this product, *note Credits::..

   *IMPORTANT:*

   Send bug (error) reports, questions and comments to the mailing list
at <mysql@tcx.se>.

   Please use the `mysqlbug' script when posting bug reports or
questions about *MySQL*. `mysqlbug' will gather some information about
your system and start your editor with a form in which you can describe
your problem. Bug reports might be silently ignored by the *MySQL*
maintainers if there is not a good reason included in the report as to
why `mysqlbug' has not been used. A report that says 'MySQL does not
work for me. Why?'  is not considered a valid bug report.

   The `mysqlbug' script can be found in the `scripts' directory in the
distribution, that is, `where-you-installed-mysql/scripts'.

What is *MySQL*?
================

   *MySQL* is a SQL (Structured Query Language) database server.  SQL
is the most popular database language in the world. *MySQL* is a client
server implementation that consists of a server daemon `mysqld' and
many different client programs/libraries.

   The main goals of *MySQL* are speed and robustness.

   The base upon which *MySQL* is built is a set of routines that have
been used in a highly demanding production environment for many years.
While *MySQL* is still in development, it already offers a rich and
highly useful function set.

   The official way to pronounce *MySQL* is 'My Ess Que Ell' (Not
MY-SEQUEL).

About this manual
=================

   This manual is currently available in TeXInfo, Raw text, Info and
HTML versions. A PostScript version is available to download separately
because of its size.

   The primary document is the TeXInfo file. The HTML version is
automatically produced with a modified `texi2html'. The ASCII and Info
versions are produced with `makeinfo'. The Postscript version is
produced using `texi2dvi' and `dvips'.

   This manual is written and maintained by David Axmark, Michael
(Monty) Widenius and Kim Aldale. For other contributors, *note
Contrib::..

History of *MySQL*
==================

   We once started off with the intention to use `mSQL' to connect to
our own fast low level (ISAM) tables. However, after some testing we
came to the conclusion that `mSQL' was not fast or flexible enough for
our needs. This resulted in a new SQL interface to our database but
with almost the same API interface as `mSQL'. This API was chosen to
ease porting of third-party code.

   It is not perfectly clear where the name *MySQL* derives from. Our
base directory and a large amount of our libraries and tools have had
the prefix 'my' for well over 10 years. However, Monty's daughter (some
years younger) is also named My. So which of the two gave its name to
*MySQL* is still a mystery, even for us.

The main features of *MySQL*
============================

   * Fully multi-threaded using kernel threads. That means it easily can
     use multiple CPUs if available.

   * C, C++, JAVA, Perl, Python and TCL API's. *Note Clients::.

   * Works on a lot of different platforms. *Note Which OS::.

   * Lots of column types like: signed/unsigned integers 1,2,3,4 and 8
     bytes long, `FLOAT', `DOUBLE', `CHAR', `VARCHAR', `TEXT', `BLOB',
     `DATE', `DATETIME', `YEAR', `SET' and `ENUM' types. *Note Column
     types::.

   * Very fast joins using an optimised one-sweep multi-join.

   * Full function support in the SELECT and WHERE parts. Example:
     `select column1 + column2 from table where column1/column2 > 0'.

   * SQL functions are implemented through a highly optimised class
     library and should be as fast as they can get! Usually there
     shouldn't be any memory allocation at all after the query
     initialisation.

   * Full support for SQL `GROUP BY' and `ORDER BY'. Support for group
     functions (`COUNT', `AVG', `STD', `SUM', `MAX' and `MIN').

   * Support for `LEFT OUTER JOIN' with ANSI SQL and ODBC syntax.

   * One can mix tables from different databases in the same query (in
     3.22).

   * A privilege and password system which is very flexible and secure.
     Allows host based verification.

   * Secure passwords since all password traffic on the net is
     encrypted.

   * ODBC Open-DataBase-Connectivity for Windows95 (with source). All
     ODBC 2.5 functions and lots of others. So you can, for example,
     use Access to connect to your *MySQL* server. *Note ODBC::.

   * Very fast B-tree disk tables with index compression.

   * 16 indexes/table. Each index may consist of 1 to 15 columns/parts
     of columns. Maximum index length is 256 bytes (but may be changed
     when compiling *MySQL*). An index may be a prefix of a CHAR field.

   * Fixed and variable length records.

   * In-memory hash tables which are used as temporary tables.

   * Handles large databases (we are using *MySQL* with some databases
     that contain 50,000,000 records).

   * All columns have default values. One can always use INSERT on any
     subset of columns.

   * Uses GNU `autoconf' for portability.

   * Written in C and C++. Tested with a broad range of different
     compilers.

   * A very fast thread-based memory allocation system.

   * No memory leaks. Tested with a commercial memory leakage detector
     (`purify').

   * A very fast table check, optimize and repair utility. *Note
     isamchk::.

   * All data saved in ISO8859_1 format. All comparisons for normal
     string columns are case insensitive.

   * Full ISO8859_1 (Latin1) support. For example, Scandinavian  is
     allowed in table and column names.

   * Sorts by ISO8859_1 Latin1 (the Swedish way at the moment). It is
     possible to change this in the source by adding new sort order
     arrays. To see an example of very advanced sorting, look at the
     Czech sorting code. *MySQL* supports a lot of different character
     sets that can be specified at compile time.

   * Aliases on tables and columns as in the SQL92 standard.

   * `DELETE', `INSERT', `REPLACE', and `UPDATE' return how many rows
     were affected.

   * Function names do not clash with table or column names. For
     example ABS is a valid column name. The only restriction is that
     space is not allowed between a function name and the '(' when
     using functions.  *Note Reserved words::.

   * All *MySQL* programs support the options `--help' and `-?'  for
     help.

   * The server currently supports error messages to clients in many
     languages. *Note Languages::.

   * The clients use a TCP connection or Unix socket when connecting to
     the *MySQL* server.

   * The *MySQL* specific `SHOW' command that can be used to retrieve
     information about databases, tables and indexes. The `EXPLAIN'
     command can be used to check how the optimizer resolves a query.
     User commands as `show tables', `SHOW INDEX FROM table' and `show
     columns from table'.

General SQL information and tutorials
=====================================

   There is one SQL tutorial on the net at
`http://w3.one.net/~jhoffman/sqltut.htm'.

   This book has been recommended by a lot of people on the *MySQL*
mailing list:

     Judith S. Bowman, Sandra L. Emerson and Marcy Darnovsky
     "The Practical SQL Handbook: Using Structured Query Language"
     Second Edition
     Addison-Wesley
     ISBN 0-201-62623-3
     http://www.awl.com

   And another book also recommended by people on the *MySQL* mailing
list:

     Understanding SQL
     ISBN 0-89588-644-8
     Publisher Sybex 510 523 8233
     Alameda, CA USA

Useful *MySQL*-related links
============================

Some web development tools which support *MySQL*
------------------------------------------------

   * PHP: A server-side HTML-embedded scripting      language (http://www.php.net)

   * *MySQL* + PHP demos (http://www.wernhart.priv.at/php/)

   * WWW-SQL: Display databases      information (http://www.daa.com.au/~james/www-sql/)

   * Minivend: A Web shopping cart (http://www.minivend.com/minivend/)

   * HeiTML: A server-side extension of HTML and      a 4GL language at the same time (http://www.heitml.com)

   * Metahtml: A Dynamic Programming Language      for WWW Applications (http://www.metahtml.com/)

   * VelocityGen for Perl and TCL (http://www.binevolve.com/)

   * Hawkeye Internet Server Suite (http://hawkeye.net)

Web servers with *MySQL* tools
------------------------------

   * An Apache      authentication module (http://bourbon.netvision.net.il/mysql/mod_auth_mysql/)

   * The Roxen Challenger Web server (http://www.roxen.com/)

Examples
--------

   * A      Contact Database using *MySQL* and PHP (http://www.webtechniques.com/features/1998/01/note/note.shtml)

Other *MySQL* related links.
----------------------------

   * Comercial Web defect      tracking system (http://www.open.com.au/products.html)

   * PTS: Project Tracking System (http://www.stonekeep.com/pts/)

   * Job and software traking      system (http://tomato.nvgc.vt.edu/~hroberts/mot)

   * Support for BIND (The Internet      Domain Name Server) (http://www.seawood.org/msql_bind/)

   * A REXX interface      to SQL databases (http://www.lightlink.com/hessling/rexxsql.html)

   * Registry of Web providers who      support *MySQL* (http://www.wix.com/mysql-hosting)

   * TCL interface (http://www.binevolve.com/~tdarugar/tcl-sql/)

   * Patch for mSQL TCL (http://www.gagme.com/mysql)

   * Full-text search engine using      *MySQL* (http://www.pi.net/~hverbeek/mysql/)

   * WDB: Web browser as      a universal front end to databases (http://www.lava.net/beowulf/programming/wdb/)

   * EasySQL: An ODBC like driver manager
     (http://www.amsoft.ru/easysql/)

   * Network Database Connection For Linux (http://www.fastflow.com/)

   * ExportSQL: A script      to export data from Access (http://www.cynergi.net/non-secure/exportsql/)

   * SAL (Scientific      Applications on Linux) *MySQL* entry (http://SAL.KachinaTech.COM/H/1/MYSQL.html)

   * *MySQL* Apps and Utilities      Listing (http://www.cgishop.com/bin/mysqllist)

   * The *MySQL*      reference manual in Adobe PDF format (http://www.luth.se/~goggi/proj/mysql/man/mysql.pdf)

   * A consulting company      which mentions *MySQL* in the right company. (http://www.infotech-nj.com/itech/index.shtml)

   * PMP Computer Solutions. Database developers      using mySQL and mSQL (http://www.pmpcs.com/)

   * Airborne Early Warning Association  (http://www.aewa.org)

   * *MySQL*      binding to Free Pascal (http://tfdec1.fys.kuleuven.ac.be/~michael/fpc-linux/mysql)

   *

     C headers for Pascal (http://tfdec1.fys.kuleuven.ac.be/~michael/fpc-linux/mysql/mysql.html)

General database links.
-----------------------

   * Database Jump Site (http://www.pcslink.com/~ej/dbweb.html)

   * The JDBC database access API (http://java.sun.com/products/jdbc/)

   * Homepage of the webdb-l      (Web Databases) mailing list. (http://black.hole-in-the.net/guy/webdb/)

   * perl DBI/DBD modules      homepage (http://www.hermetica.com/technologia/DBI/)

   There are also many web pages that use *MySQL*. *Note Users::. Send
any additions to this list to <webmaster@tcx.se>.

What are stored procedures and triggers and so on?
==================================================

   A stored procedure is a set of SQL commands that can be stored and
compiled in the server. After this, the client doesn't have to issue
the whole query but can refer to the stored procedure. This gives some
more speed because the query only has to be parsed once and less data
need be sent between the server and the client. You can also raise the
conceptual level by having libraries of functions in the server.

   A trigger is a stored procedure that is invoked when something
happens.  For example, one can install a stored procedure that checks
every delete to a transaction table and does an automatic delete on the
corresponding customer when all his transactions are deleted.

   To see when *MySQL* might get these functions, *note Todo::..

*MySQL* mailing lists and how to ask questions/give error (bug) reports
***********************************************************************

Subscribing to/un-subscribing from the *MySQL* mailing list
===========================================================

   Requests to be added to or dropped from the *MySQL* list should be
sent to the electronic mail address <mdomo@tcx.se>. Sending a one-line
message saying either `subscribe mysql' or `unsubscribe mysql' will
suffice. If your reply address is not valid you may use `subscribe
mysql your@address.your-domain' or `unsubscribe mysql
your@address.your-domain'.

   Please *do not* send mail about [un]subscribing to <mysql@tcx.se>
since any mail sent to this address is automatically forwarded to
hundreds of other users.

   Your local site may have many subscribers to <mysql@tcx.se>. In that
case, it may have a local mailing list, so that a single message from
`tcx.se' is sent to the site and propagated to the local list. In such
cases, please contact your system administrator to be added to or
dropped from the local <mysql@tcx.se> list.

   Mail to `mdomo' is handled automatically by majordomo.

   The following mailing lists exist:

`mysql-announce'
     This is for announcement of new versions of *MySQL* and related
     programs. This is a low volume list that we think all *MySQL*
     users should be on.

`mysql'
     The main list for general *MySQL* discussion. Please note that
     some things should go to the specialized lists. It you post to the
     wrong list you may not get an answer!

`mysql-digest'
     The above list in digest form. That means you get all messages in
     one mail once a day.

`mysql-Java'
     Discussion about *MySQL* and JAVA. Mostly about the JDBC drivers.

`mysql-win32'
     All things concerning *MySQL* on Microsoft operating systems like
     Windows/NT.

`myodbc'
     All things concerning connection to *MySQL* with ODBC.

`msql-mysql-modules'
     A list about the Perl support in *MySQL*.

`msql-mysql-modules-digest'
     A digest version of the above.

   You subscribe/unsubscribe to all lists in the same way as described
above. Just exchange `mysql' with the list name.

Asking questions or reporting bugs
==================================

   Before you ask a question on the mailing list, it is a good idea to
check this manual. If you can't find an answer here, check with your
local *MySQL* expert. If you still can't find an answer to your
question go ahead and read the next section about how to send mail to
<mysql@tcx.se>.

I think I have found a bug. What information do you need to help me?
====================================================================

   If you can, please use the `mysqlbug' script that can be found in
the scripts directory in the distribution. If that is not possible,
remember to specify (if relevant) the following. Note that it is
possible to answer a letter with too much information but not one with
too little.  You should always use `mysqlbug' if your question is any
way related to a *MySQL* version you are using!

   `mysqlbug' should automatically find most of the following
information, but if something important is missing please include this
in your question!

  1. State which version of *MySQL* you are using (for example
     mysql-3.21.22.tgz). You can find out which version you are running
     by typing `mysqladmin version'.

  2. The manufacturer and model of machine you are working on.

  3. The operating system. For most operating systems you can get this
     from `uname -a'.

  4. Sometimes the amount of memory (real and virtual) is also relevant.

  5. Write in the mail that you have checked the reference manual and
     mail archive so others know that you have tried to solve your
     problem yourself.

  6. If the bug occurs during compilation, include the exact error
     messages and also a few lines around the offending code in the
     file from which you got the error.

  7. If this is a run-time bug, please describe exactly how you got the
     error. If you can include a test program, with tables, which shows
     the error, you will probably get a more explicit answer.

  8. If you can't produce a test case in a few rows or if the the test
     table is too big to be mailed to everyone (more than 10 rows) you
     should dump your tables using `mysqldump' and make a README that
     describes your problem. `tar' and `gzip' or `zip' the files and
     `ftp' the archive to ftp://www.tcx.se/pub/mysql/secret (ftp://www.tcx.se/pub/mysql/secret).  Then send a short description of
     the problem to <mysql@tcx.se>.

  9. If the question is related to the privilege system, please include
     the output of `mysqlaccess', the output of `mysqladmin reload' and
     all error messages you get when trying to connect!  You should do
     the tests in the above order!

 10. If the questions is related to the privilege system, please include
     the output of mysqlaccess,  the output of 'mysqladmin reload' and
     and all error messages you get when trying to connect !  You
     should do the test in the above order !

   If you are a support customer, please post the bug report to the
specified mailing list for higher priority treatment.

   When answers are sent to you individually and not to the mailing
list, it is considered good etiquette to summarise the answers and mail
them to the mailing list.

*MySQL* keeps crashing
----------------------

   Since it is very hard to know why something is crashing please do
one of the following things.

   First try to check whether or not things that work for others crash
for you:

   * Have you tried the benchmarks?  This should test *MySQL* rather
     well. You can also add code that simulates your application!

   * Try also `fork_test.pl' and `fork2_test.pl'.

   * Check the reference manual for information about debugging
     `mysqld'.

   * Recompile *MySQL* with the `--with-debug' switch to `configure'.
     This will include a safe memory allocator that can find some
     errors. This also gives a lot of output about what is happening.

   * Use `mysqld --log' and try to determine whether or not some
     specific query kills it. 95% of all bugs are related to some
     specific query!

   * Have you applied the latest patches for your Operating System?

   * Use `--skip-locking'.

   * Have you tried `mysqladmin proc' when it dies?

   * Run the command `mysqladmin -i 5 status' in a separate window to
     output statistics.

   * Try the following:
       1. Start `mysqld' with `gdb' (or another debugger).

       2. Run your test scripts.

       3. Do `back' (or the backtrace command in your debugger) when
          `mysqld' core dumps.

   * Try to simulate your application with a perl script to force
     *MySQL* to crash/misbehave.

   * Or send a normal bug report. *Note Bug reports::. But be even more
     detailed than normally. Since *MySQL* works for a lot of people it
     may be that the crash results from something that exists only on
     your computer. For example, a system library error.

Guidelines for answering questions on the mailing list
======================================================

   Try to make your answer broad enough that people other than the
original poster may benefit from it. If you consider your answer to
have broad interest, you may want to post it to the mailing list
instead of replying directly to the individual who asked. In such
cases, please make sure that your answer is not a duplication of a
previous answer.

   Try to summarise the essential part of the question in your reply,
but don't feel obliged to quote the whole question.

Licensing or When do I have/want to pay for *MySQL*?
****************************************************

   Basic licensing issues:

   * The easiest way to pay for *MySQL* is to use the license form at
     TcX's secure server at `https://www.tcx.se/license.htmy'

   * We hope everybody understands that you only have to pay if you are
     selling *MySQL* directly or selling a product which includes the
     *MySQL* server.  You may not include *MySQL* in a distribution if
     you charge for some part of it.  For internal use you do not have
     to pay us if you do not want to.

   * The client code is in the Public Domain or under the GPL
     (readline).  You do not need a license to include client code in
     commercial programs.

   * We may add some additional functionality in the commercial
     version. The likely test candidate for this is fast compressed
     read-only databases. The current server includes support to read
     such databases but not the packing tool. If we get enough revenue
     from support we will probably release this under the same license
     as the other stuff.

   * But if you like *MySQL* and want to encourage further development
     you are welcome to purchase a license or support.

   *Note Public::.

How much does *MySQL* cost?
===========================

   For normal use *MySQL* costs nothing. When you sell *MySQL* directly
or as a part of another product you have to pay for it. *Note Public::.

   The client access part of *MySQL* is in the public domain. The
command line client includes parts that are under the GNU Public License
(readline).

   These are our current license prices. All prices are in US Dollars.
If you pay by credit card, the currency is FIM (Finish Marks) so the
prices will differ slightly.

Number of licenses            Price/Copy             Total                  
1                             US $200                US $200                
10 pack                       US $150                US $1500               
50 pack                       US $120                US $6000               

   For high volume (OEM) purchases the following prices apply:

licenses               Price/Copy     Minimum at     Minimum Payment        
                                      one time                              
100-1000               $40            100            $4000                  
1000-2500              $25            200            $5000                  
2500-5000              $20            400            $8000                  

   The OEM prices require that you act as a middle-man for eventual
problems/extension requests from users. We also require that the OEM
customer has a support contract.

   If you have a low-margin high-volume product, you can always talk to
us about other terms (for example a percent of the sale price). If you
do, please be informative about your product, pricing, market and any
other information that may be relevant.

How do I get commercial support?
================================

   A full-price license includes really basic support. This means that
we are trying to answer any relevant question. If the answer is in the
documentation, we are going to direct you to the relevant
documentation. If you do not have a license/support we will probably not
answer at all.

   If you discover what we consider a real bug, we are likely to fix it
in any case. But if you pay for support we will notify you about the fix
status instead of just fixing it in a later release.

   More comprehensive support is sold separately.

Types of commercial support
---------------------------

   The various types of commercial support are described in the
following sections.  You are entitled to upgrade from any lower level
of support to a higher level of support for the difference between the
prices of the two support levels.

Basic email support
...................

   One year of basic email support costs $200 (USD).

   It includes:
  1. For *MySQL*-specific questions that don't belong on the *MySQL*
     mailing list (<mysql@tcx.se>), you can contact
     <mysql-support@tcx.se>. Remember to give your registration number
     and expiration date when mailing any list to ensure a quick
     response.

  2. We guarantee a timely answer for your emails.  We can't guarantee
     that we can solve any problem, but at least you will receive an
     answer if we can contact you by email.

  3. Your suggestions for the further development of *MySQL* will be
     taken into consideration. By taking email support you have already
     helped the further development of *MySQL*. If you want to have
     more input upgrade to a higher level of support.

  4. Helping with unexpected problems when installing *MySQL* from a
     binary distribution on a supported platforms.

  5. We will help you with bugs and missing features. Any bugs that are
     found are fixed for the next *MySQL* release. If the bug is
     critical for you, we will mail you a patch for it as soon the bug
     is fixed.  Critical bugs always have the highest priority for us,
     to ensure that they are fixed as soon as possible.

  6. This level of support does not cover installing *MySQL* from a
     source distribution.

  7. If you want us to help to optimize your system you have to upgrade
     to a higher level of support.

Extended email support
......................

   One year of extended email support costs $1000 (USD).

   Extended basic support contains everything in basic email support
with these additions:
  1. Your email will be dealt with before normal email support users and
     non-registered users.

  2. Your suggestions for the further development of *MySQL* will
     receive strong consideration. Simple extensions that suit the basic
     goals of *MySQL* are implemented in a matter of days. By taking
     extended email support you have already helped the further
     development of *MySQL*.

  3. In this we include a binary version of the pack_isam tool that
     supports fast compressed read-only databases (no `BLOB' or `TEXT'
     types yet). The current server includes support to read such
     databases but not the packing tool.

  4. Typical questions that are covered by extended email support are:
        * Answering and solving (within reason) questions that relate
          to (possibly) bugs in *MySQL*.  As soon as the bug is found
          and corrected, we will mail a patch for it.

        * Helping with unexpected problems when installing *MySQL* from
          a source/binary distribution on supported platforms.

        * Answering questions about missing features and offering hints
          how to go around them.

        * How to optimize `mysqld' for your situation.

  5. You are allowed to slightly alter *MySQL* TODO. This will ensure
     that the features you really need will be implemented sooner than
     otherwise.

Login support
.............

   One year of email/phone/telnet support costs $2000 (USD).

   Login support contains everything in extended basic email support
with these additions:

  1. Your email will be dealt with even before mail from extended
     support users.

  2. Your suggestions for the further development of *MySQL* will be
     taken into very high consideration  Realistic extensions that can
     be implemented in a couple of hours and that suit the basic goals
     of *MySQL* will be implemented as soon as possible.

  3. If you have a very specific problem we can try to log in on your
     system to solve the problem 'in place'.

  4. As any database vendor, we can't guarantee that we can rescue any
     data from crashed tables, but if the worst happens we will help
     you rescue as much as possible. *MySQL* has proven itself very
     reliable, but because of outside interference anything is possible.

  5. We will give you hints how to optimize your system and your
     queries.

  6. You are allowed to call a *MySQL* developer (in moderation) and
     discuss your *MySQL* related problems.

Extended login support
......................

   One year of extended email/phone/telnet support costs $5000 (USD).

   Extended login support contains everything in login support with
these additions:

  1. Your email has the highest possible priority.

  2. We will actively examine your system and help you optimize it and
     your queries. We may also optimize and/or extend *MySQL* to better
     suit your needs.

  3. You may also request special extensions just for you. For example:
          select my_calculation(column1,column2) from database;

  4. We will provide a binary version of all important *MySQL*
     distributions for your system, as long as we can get an account on
     a similar system. In the worst case we may require access to your
     system to be able to make a binary version.

  5. If you can provide accommodation and pay for traveler fares you
     can even get a *MySQL* developer to visit you and offer you help
     with your troubles. The extended login support entitles you to one
     personal encounter, but we are as always very flexible towards our
     customers!

How do I pay for licenses/support?
==================================

   Currently we can take SWIFT payments, cheques or credit cards.

   Payment should be made to:
     Postgirot Bank AB
     105 06 STOCKHOLM, SWEDEN
     
     T.C.X DataKonsult AB
     BOX 6434
     11382 STOCKHOLM, SWEDEN
     
     SWIFT address: PGSI SESS
     Account number: 96 77 06 - 3
     
     Specify: license and/or support and your name and email address.

   In Europe and Japan you can use EuroGiro (that should be cheaper) to
the same account.

   If you want to pay by cheque make it payable to "Monty Program KB".
And mail it to the address below.

     T.C.X DataKonsult AB
     BOX 6434
     11382 STOCKHOLM, SWEDEN

   If you want to pay with credit card over the Internet you can use
TcX's secure license form (https://www.tcx.se/license.htmy)

Who do I contact when I want more information about licensing/support?
======================================================================

   For commercial licensing, or if you have any questions about any of
the information in this section, please contact:

     David Axmark
     Detron HB
     Kungsgatan 65 B
     753 21 UPPSALA
     SWEDEN
     Voice Phone +46-18-10 22 80     (Swedish and English spoken)
     Fax +46-8-729 69 05             (Email *much* preferred)
     E-Mail: mysql-licensing@tcx.se

What Copyright does *MySQL* use?
================================

   There are (at least) four different copyrights on the *MySQL*
distribution.

  1. The *MySQL* specific source needed to make the `mysqlclient'
     library and programs in the `client' directory is in the public
     domain. Each file which is in the public domain has a header which
     clearly states so. This is everything in the `client' directory
     and some parts of the mysys, mystring and dbug libraries.

  2. Some small parts of the source (GNU `getopt') are covered by the
     "GNU LIBRARY LIBRARY GENERAL PUBLIC LICENSE".  See the
     `mysys/COPYING.LIB' file.

  3. Some small parts of the source (GNU `readline') are covered by the
     "GNU GENERAL PUBLIC LICENSE". See the `readline/COPYING' file.

  4. Some parts of the source (the `regexp' library) are covered by a
     Berkeley style copyright.

  5. The other source needed for the *MySQL* server is AGPL. See the
     file PUBLIC for more info.

   Our philosophy behind this is:

   - The SQL client library should be totally free so it can be
     included in commercial products without limitations.

   - People who want free access to the software we have put a lot of
     work into can have it so long they do not try to make money
     directly by distributing it for profit.

   - People who want the right to keep their own software proprietary,
     but also want the value from our work, can pay for the privilege.

   - That means normal in-house use is FREE. But if you use it for
     something important to you, you may want to support further
     development of *MySQL* by purchasing a support license.

When may I distribute *MySQL* commercially without a fee?
=========================================================

   This is a clarification of the information in the '*MySQL* FREE
PUBLIC LICENSE'. *Note Public::.

   *MySQL* may be *used* freely, including by commercial entities for
evaluation or unsupported internal use. However, *distribution* for
commercial purposes of *MySQL*, or anything containing or derived from
*MySQL* in whole or in part, requires a written commercial license from
TcX AB, the sole entity authorised to grant such licenses.

   You may not include *MySQL* "free" in a package containing anything
for which a charge is being made except as noted below.

   The intent of the exception provided in the second clause is to allow
commercial organisations operating an FTP server or a bulletin board to
distribute *MySQL* freely from it, provided that:

  1. The organisation complies with the other provisions of the FPL,
     which include among other things a requirement to distribute the
     full source code of *MySQL* and of any derived work, and to
     distribute the FPL itself along with *MySQL*;

  2. The only charge for downloading *MySQL* is a charge based on the
     distribution service and not one based on the content of the
     information being retrieved (i.e., the charge would be the same
     for retrieving a random collection of bits of the same size);

  3. The server or BBS is accessible to the general public, i.e., the
     phone number or IP address is not kept secret, and anyone may
     obtain access to the information (possibly by paying a
     subscription or access fee that is not dependent on or related to
     purchasing anything else).

   If you want to distribute software in a commercial context that
incorporates *MySQL* and you do *not* want to meet these conditions,
you should contact TcX AB to find out about commercial licensing.
Commercial licenses involve a payment, and include support and other
benefits. These are the only ways you legally can distribute *MySQL* or
anything containing *MySQL*: either by distributing *MySQL* under the
requirements of the FPL, or by getting a commercial license from TcX AB.

I want to sell a product that can be configured to use *MySQL*
==============================================================

   I want to sell a product that can be configured to use *MySQL*
although my customer is responsible for obtaining/installing *MySQL*
(or some other supported alternative). Does one of us owe you money if
my customer chooses to use *MySQL*?

   If your product REQUIRES *MySQL* to work, you would have to buy a
license. If *MySQL* just added some new features it should fall inside
normal use. For example, if using *MySQL* added logging to a database
instead of a text file it would not require a license.  This would, of
course, mean that the user has to fetch and install *MySQL* by himself.
If the program is (almost) useless without *MySQL* you would have to
get a *MySQL* license to sell your product.

I am running a commercial web server using *MySQL*
==================================================

   Do I have to get a license for my copy?

   No, you are not selling *MySQL* itself. But in this case we would
like you to purchase *MySQL* support. That is either your support of
*MySQL* or our support of you (the later is more expensive since our
time is limited).

Do I need a license to sell commercial perl/tcl/PHP/Web+ etc applications?
==========================================================================

   Is your script designed for *MySQL* alone? Does it require *MySQL*
to function at all? Or is it designed for `a database' and can run
under *MySQL*, PostgreSQL, or something else?

   If you've designed it strictly around *MySQL* then you've really
made a commercial product that requires the engine, so you need to buy
a license.

   If, however, you can support any database with a base level of
functionality (and you don't rely on anything that only *MySQL*
supports) you probably DO NOT have to pay.

   It also depends on what you're doing for the client. Are you tying
into a database you expect to already exist by the time your software is
purchased?  Then you again probably don't have to pay. Or do you plan to
distribute *MySQL* or give them detailed instructions on installing it
with your software? Then you probably do.

   One thing I'd like to suggest, folks. Look, development won't last
forever if nobody pays. I agree that buying a copy for every software
user is prohibitive compared to other products available but would it
not be courtesy for commercial developers to register their OWN copy
that they develop with?

Possible future changes in the licensing
========================================

   We may choose to distribute older versions of *MySQL* with the GPL
in the future. However these versions will be identified as *GNU
MySQL*. Also all copyright notices in the relevant files will be
changed to the GPL.

Compiling and installing *MySQL*
********************************

How do I get *MySQL*?
=====================

   You can always check *MySQL*'s home page (http://www.tcx.se/) to
read the latest news.

   But since the Internet connection at TcX is not so fast we would
*prefer* if you do the actual downloading from one of the mirrors below.

   Please report bad/not updated mirrors to <webmaster@tcx.se>.

   Europe:
   *    Austria WWW [Univ. of      Technology/Vienna] (http://gd.tuwien.ac.at/db/mysql/)

   *    Bulgaria FTP [Naturella] (ftp://ftp.ntrl.net/pub/mirror/mysql)

   *    Czech Republic WWW [CESNET] (http://mirror.opf.slu.cz/mysql/)

   *    Denmark WWW [Ake] (http://mysql.ake.dk)

   *    Denmark WWW [SunSITE] (http://SunSITE.auc.dk/mysql/)

   *    Denmark FTP [SunSITE]
     (ftp://SunSITE.auc.dk/pub/databases/mysql/)

   *    Estonia WWW [Tradenet] (http://mysql.tradenet.ee)

   *    France WWW [minet] (http://www.minet.net/devel/mysql/)

   *    Germany      WWW [Wolfenbuettel] (http://www.fh-wolfenbuettel.de/ftp/pub/database/mysql/)

   *    Germany WWW [Staufen] (http://mysql.staufen.de/)

   *    Hungary WWW      [Xenia] (http://xenia.sote.hu/ftp/mirrors/www.tcx.se-mysql/)

   *    Israel WWW [Netvision] (http://mysql.netvision.net.il/)

   *    Israel FTP      [Netvision] (ftp://mysql.netvision.net.il/mirrors/mysql/)

   *    Italy WWW [Matrice] (http://www.matrice.it/risorse/mysql/)

   *    Poland WWW [Sunsite] (http://sunsite.icm.edu.pl/mysql/)

   *    Poland FTP [Sunsite] (ftp://sunsite.icm.edu.pl/pub/unix/mysql/)

   *    Portugal WWW [Telenet] (http://mysql.telenet.pt)

   *    Russia FTP [Cityline] (ftp://ftp-mysql.cityline.ru/pub/MySQL)

   *    Romania WWW [Timisoara] (http://www.dnttm.ro/mysql)

   *    Romania FTP [Timisoara] (ftp://ftp.dnttm.ro/pub/mysql)

   *    Romania WWW [Bucharest] (http://www.lbi.ro/MySQL)

   *    Romania FTP [Bucharest] (ftp://ftp.lbi.ro/mirrors/ftp.tcx.se)

   *    Sweden WWW [Sunet] (http://ftp.sunet.se/pub/unix/databases/relational/mysql/)

   *    Sweden      FTP [Sunet] (ftp://ftp.sunet.se/pub/unix/databases/relational/mysql/)

   *    UK WWW [Omnipotent/UK] (http://mysql.omnipotent.net/)

   *    UK FTP [Omnipotent/UK] (ftp://mysql.omnipotent.net/)

   *    UK WWW [PLiG/UK] (http://ftp.plig.org/pub/mysql/)

   *    UK FTP [PLiG/UK] (ftp://ftp.plig.org/pub/mysql/)

   North America:
   *    Canada WWW [Polaris Computing] (http://mysql.polaris.ca/)

   *    Canada WWW [Tryc] (http://web.tryc.on.ca/mysql/)

   *    Canada WWW [Cyberus] (http://mysql.cyberus.ca/)

   *    Canada FTP [Cyberus] (ftp://mysql.cyberus.ca/)

   *    USA WWW [Hurricane Electric/San Jose] (http://mysql.he.net)

   *    USA WWW [Buoy/New York] (http://www.buoy.com/mysql/)

   *  USA WWW [Hypernet      Communications/Dallas] (http://epsilon.hpnc.com/mysql)

   *  USA WWW [Hurricane Electric/California] (http://mysql.he.net)

   *    USA FTP [Netcasting/West      Coast] (ftp://ftp.netcasting.net/pub/mysql/)

   *    USA WWW [Savages/Oregon] (http://mysql.savages.com)

   *    USA WWW [Circle Net/North Carolina] (http://www.mysql.net)

   *    USA WWW [Gina net/Florida] (http://www.gina.net/mysql/)

   *    USA FTP      [DIGEX] (ftp://ftp.digex.net/pub/database/mysql/index.html)

   South America:
   *    Chile WWW      [Amerikanclaris] (http://www.labs.amerikanclaris.cl/mysql)

   *    Chile FTP      [Amerikanclaris] (ftp://ftp.amerikanclaris.cl/pub/mysql)

   Asia:
   *    Korea WWW [KREONet] (http://linux.kreonet.re.kr/mysql/)

   *    Japan WWW [HappySize] (http://www.happysize.co.jp/mysql/)

   *    Japan FTP [HappySize] (ftp://ftp.happysize.co.jp/pub/mysql/)

   *    Singapore WWW [Com5 Productions] (http://mysql.com5.net)

   *    Singapore FTP [Com5 Productions] (ftp://ftp.com5.net/pub/mysql)

   *    Taiwan WWW [NCTU] (http://www.iem.nctu.edu.tw/data/mysql)

   Australia:
   *    Australia WWW      [AARNet/Queensland] (http://mirror.aarnet.edu.au/mysql)

   *    Australia FTP      [AARNet/Queensland] (ftp://mirror.aarnet.edu.au/pub/mysql)

   *    Australia WWW [Blue Planet/Melbourne] (http://mysql.bluep.com/)

   *    Australia FTP [Blue      Planet/Melbourne] (ftp://mysql.bluep.com/mirror1/mysql/)

Which *MySQL* version should I use?
===================================

   The first decision is whether you want to use the latest development
release or the last stable release.

   Normally if you are starting with development we recommend going with
the development release. This is because there are usually no really bad
bugs in the development release and you can easily test it on your
machine with the crash-me and benchmark tests. *Note Benchmarks::.

   The second decision is whether you want a source release or a binary
release.

   If you want to run *MySQL* on a platform that has a current binary
release, use that. A binary version of *MySQL* is easier to install.

   If you want to read (and/or modify) the C and C++ code that makes up
*MySQL* you should always get a source distribution. The code is always
the ultimate manual. The source distribution also contains more tests
and examples than the binary distribution.

   To clarify our naming schema:

   All *MySQL* versions are run through our standard test and the
benchmarks to ensure that they are relatively safe to use.  The standard
tests are also extended the whole time to test for all previously found
bugs, so it gets better the whole time.

   The *MySQL* release numbers consist of 3 numbers and a suffix.

   So a release name like `mysql-3.21.17-beta' means:

The first number. In this case 3
     This describes the file format. So all version 3 releases have the
     same file format. When a version 4 appears, every table will have
     to be converted to the new format (nice tools for this will be
     included, of course).

The second number. In this case 21
     This is the release level. Normally there are two to choose from.
     One is the release/stable branch and the other is the development
     branch. Normally both are stable but the development version may
     have quirks, missing documentation and may fail to compile on some
     systems.

The third number. In this case 17
     This is the version number. This is incremented for each release.
     Usually you want the latest version for the release you have
     choosen.

The suffix. In this case beta
        * Alpha means that some new large code section exists which
          hasn't been tested to 100%. Known bugs should be documented
          in the News section (usually there are none). There are also
          new commands and extensions in most alpha releases.

        * Beta means that all new code has been tested. No major new
          things are added. There should be no known bugs.

        * Gamma is a beta that has been around a while and seems to
          work fine.  This is what many other companies call a release.

        * Release (no extension) means that the version has been run
          for a while at many different sites without any bug reports
          (except platform-specific bugs).

   Note that all releases have at least been tested with:

An internal test suite
     This is part of a production system for a customer. It has many
     tables and with many megabytes of data and lots of tables.

The *MySQL* benchmark suite
     This runs a range of common queries. It is also a test to see
     whether the latest batch of optimisations actually made the code
     faster. *Note Benchmarks::.

The crash-me test
     This tries to find out what the database supports and which
     limitations it has. *Note Benchmarks::.

   Another test is our internal production. We usually use the latest
version for this (at least on one machine) and we have more than 100
gigabytes of data to work with.

How/when will you release updates?
==================================

   We are using the following policy when updating *MySQL*:

   Each minor update will increment the last number in the version
string. When there are major new features or minor incompatibilities
with previous versions, the second number in the version string will be
incremented. When the file format changes the first number will be
increased.

   * Stable tested releases are meant to appear about 1-2 times a year.
     But if small bugs are found, a release with only bug-fixes will be
     released.

   * Working releases are meant to appear about every 1-8 weeks.

   * Binary releases for some platforms will be made for major releases
     by us. Other people may make binary releases for other systems but
     probably less frequently.

   * We usually make patches available as soon as we have located and
     fixed small bugs.

   * For non-critical but annoying bugs, we will make patches available
     if they are sent to us. Otherwise we will combine many of them
     into a bigger patch.

Which operating systems does *MySQL* support?
=============================================

   We use GNU autoconf so it is possible to port *MySQL* to all modern
systems with working Posix threads and a C++ compiler. The client code
requires C++ but not threads. We use/develop the software ourselves
primarily on Sun Solaris (versions 2.5 & 2.6) and some on RedHat Linux
5.0.

   The following OS/thread packages have been reported to compile
*MySQL* successfully. Note that for many OSes the native thread support
only works in the latest versions.

   * Solaris 2.5 & 2.6 with native threads.

   * SunOS 4.x with the included MIT-pthreads package.

   * BSDI 2.x with the included MIT-pthreads package.

   * BSDI 3.0 and 3.1 native threads.

   * SGI IRIX 6.x with native threads.

   * AIX 4.x whith native threads.

   * DEC UNIX 4.x with native threads.

   * Linux 2.0+ with LinuxThreads 0.5, 0.6 and 0.7.

   * FreeBSD 2.x with the included MIT-pthreads package.

   * FreeBSD 3.x with native threads.

   * SCO OpenServer with a recent port of the FSU-threads package.

   * NetBSD 1.3 Intel and NetBSD 1.3 Alpha.

   * Openbsd 2.1

   * HP-UX 10.20 with the included MIT-pthreads package.

   * Win95 and NT.  This version is currently only available for users
     with a *MySQL* license or *MySQL* email support.

Compiling *MySQL* from source code
==================================

   What you need:

  1. GNU `gzip' to uncompress the distribution.

  2. A reasonable `tar' to unpack the distribution. GNU `tar' is known
     to work.

  3. A working ANSI `C++' compiler. gcc >= 2.7, SGI C++, and SunPro C++
     are some of the compilers that are known to work. `libg++' is not
     needed when using `gcc'.

  4. A good `make' program. If you have problems we recommend trying GNU
     `make'.

Quick installation overview
---------------------------

   Unpack the `tar' archive in a directory. The `tar' file should have
a name like `mysql-VERSION.tar.gz' (VERSION is a number like
3.21.33).  When you unpack the archive, a directory named
`mysql-VERSION' should be created.

`zcat mysql-VERSION.tar.gz | tar xvf -'
     Unpack the distribution into the current directory.

`cd mysql-VERSION'
     Change directory.

`./configure'
     Configure the release. Here you might want to add some options.
     For a list of configure options use `./configure --help'.

`make'
     Compile everything.

`make install'
     Install everything.

`./scripts/mysql_install_db'
     Set up the *MySQL* privilege tables. This needs to be done only
     the first time you install *MySQL*. You may want to edit this
     script before running it to get right initial permissions for
     users to connect to the database.  *Note mysql_install_db::

`'installation_directory'/bin/mysqladmin version'
     Check to see whether or not the server is running.
     'installation_directory' is `/usr/local' unless you added some
     options to `./configure'.  `mysqladmin' should produce output
     similar to that shown below, although it likely will not be
     exactly the same on your system:
          mysqladmin  Ver 6.3 Distrib 3.21.17, for pc-linux-gnu on i686
          TCX Datakonsult AB, by Monty
          
          Server version          3.21.17-alpha
          Protocol version        10
          Connection              Localhost via UNIX socket
          TCP port                3306
          UNIX socket             /tmp/mysql.sock
          Uptime:                 16 sec
          
          Running threads: 1  Questions: 20  Reloads: 2  Open tables: 3

   Remember that if you reconfigure *MySQL* you have to do `rm
config.cache' or `make distclean' before running `./configure' again!

   GNU `make' is always recommended and is sometimes required.

Usual configure switches
------------------------

   Some of the options you may want to use when you run `./configure'
are described below:

   * To compile only the client use `--without-server'. If you only
     want to have the client library and don't have a C++ compiler, you
     can remove the code in `configure' (in the source distribution)
     that tests for the C++ compiler and then run `./configure' with
     `--without-server'. In this case, ignore any warnings about
     `mysql.cc' (the only *MySQL* client that needs C++).

   * If you don't want to have your data under `/usr/local/var' use
     something like: `--prefix=/usr/local' or `--prefix=/usr/local
     --localstatedir=/usr/local/data/mysql'.

   * If you don't want to have your sockets in the default place
     (default is `/tmp' or `/var/run') use
     `--with-unix-socket-path=absolute_file_name'.

   * If you get errors when compiling `sql_yacc.yy' such as:

     `Internal compiler error: program cc1plus got fatal signal 11' or
     `Out of virtual memory' you can try the `configure' switch
     `--with-low-memory'.  This adds `-fno-inline' to the compile line
     if you are using gcc and `-O0' if you are using something else.
     The problem is that `gcc' requires about 180M to compile
     `sql_yacc.cc' with inline functions.

   * If you want to compile statically-linked programs for a binary
     distribution, to get more speed or to work around problems with
     some RedHat distributions, configure with `LDFLAGS=-static
     ./configure'.

   * If you are using `gcc' and don't have g++ or libstdc++ installed
     you can configure with: `CC=gcc CXX=gcc ./configure'.

   * If you don't want *MySQL* to use `DEFAULT' values at all, so that
     you get an error for any `INSERT's that don't specify all `NOT
     NULL' columns, configure with `CXXFLAGS=-DDONT_USE_DEFAULT_FIELDS
     ./configure'.

   * Changing the default character set:

     By default *MySQL* will use the ISO8859-1 (Latin1) character set.
     You may change by specifying the `configure' switch
     `--with-charset=charset', where [charset] may be one of `big5',
     `czech', `danish', `dec8', `dos', `german1', `hp8', `koi8_ru',
     `latin1', `latin2', `swe7', `usa7', `ujis' or `sjis'.

     *Note Character sets::.

     If you want to convert characters between the server and the
     client, you should take a look at the `SET OPTION CHARACTER SET'.
     *Note Set option::.

     *Warning:* If you change character sets after having created a
     table you will have to run `isamchk -r -q' on every table.
     Otherwise things will be sorted incorrectly in some cases (but not
     all!).

   * OS/computer-specific switches can be found in the OS-specific
     section later in this chapter.

Applying a patch
----------------

   Sometimes patches appear on the mailing list. To apply them, do
something like this:

     cd 'old-mysql-source-distribution-path'
     gunzip < patch-file-name.gz | patch -p1
     
     rm config.cache
     make clean

   And then follow the instructions for a normal source install from the
`./configure' step.

   And then restart your *MySQL* server.

Problems compiling?
===================

   If your compile fails with an error such as:

     configure: error: installation or configuration problem: C++ compiler
     cannot create executables.

   Try setting the environment variable `CXX' to `"gcc -O3"' (If you
are using `gcc').  For example `CXX="gcc -O3" ./configure'. If you use
this you don't need to have libg++ installed!

   If you have any problems with using g++, or libg++ or libstdc++, you
can probably always solve them by configuring as above!

   You can also install libg++. By default `configure' picks `c++' as a
compiler name and GNU `c++' links with `-lg++'.

  1. If your compile fails with the following error:
          making all in mit-pthreads
          make: Fatal error in reader: Makefile, line 18: Badly formed macro assignment
          or
          make: file `Makefile' line 18: Must be a separator (:
     This means you have to upgrade your make to GNU `make'.

  2. If you want to add flags to your C or C++ compiler, add the flags
     to the CFLAGS and CXXFLAGS environment variables. For example:

          CC=gcc
          CFLAGS=-O6
          CXX=gcc
          CXXFLAGS=-O6
          export CC CFLAGS CXX CXXFLAGS

  3. If your `make' stops with
          Can't find Makefile.PL

     Then you should try using GNU `make'. Solaris and FreeBSD are
     known to have troublesome `make' programs.

  4. If you get error messages from `make' or error messages of the
     type:

          pthread.h: No such file or directory

     This means you have to upgrade your `make' to GNU `make' (GNU
     `make' version 3.75 is known to work).

  5. If you get a error message like:

          client/libmysql.c:273: parse error before `__attribute__'

     This means you need to upgrade your `gcc' compiler (2.7.2 is known
     to work).

  6. If `configure' fails, and you are going to send mail to
     <mysql@tcx.se>, please include any lines from `config.log' that
     you think can help solve the problem.  Also include a couple of
     lines of the last output from `configure' if `configure' aborts.
     Post the bug using the `mysqlbug' script.

     *PLEASE ALWAYS USE `mysqlbug'* when posting questions to
     <mysql@tcx.se>. *Note Bug reports::.

     Even if the problem isn't a bug, `mysqlbug' gathers some system
     information that will help others solve your problem!

  7. If you need to debug `mysqld' or a *MySQL* client, run
     `./configure --with-debug=yes' and link your clients with the new
     client library.

     Before running a client you should do:
          MYSQL_DEBUG=d:t:O,/tmp/client.trace
          export MYSQL_DEBUG

     This causes clients to generate a trace file in
     `/tmp/client.trace'.

  8. If you get three errors when compiling `mysqld' like this:
          cxx: Error: mysqld.cc, line 645: In this statement, the referenced type of
               the pointer value "&length" is "unsigned long", which is not compatible
               with "int".
          new_sock = accept(sock, (struct sockaddr *)&cAddr, &length);

     Then `configure' didn't detect the type of the last argument to
     `accept()', `getsockname()' and `getpeername()'.  Search in
     `config.h' (generated by `configure') for the line:

          /* Define as the base type of the last arg to accept */
          #define SOCKET_SIZE_TYPE ###

     and change `###' to `size_t' or `int', depending on your operating
     system.  (Note that you will have to do this each time you run
     `configure', since doing so regenerates `config.h'.)

  9. If you have problem with your own client code, test first with
     `mysql --debug=d:t:o,/tmp/client.trace' before mailing a bug
     report. *Note Bug reports::.

General compilation notes
=========================

   All *MySQL* programs compile clean (no warnings) for us (on Solaris
using `gcc'). On other systems, warnings may occur due to differences
in system include files. See below for warnings that may occur when
using MIT-pthreads.

   You probably have to use `bison' to compile `sql_yacc.yy'.  If you
get an error like:
     "sql_yacc.yy", line xxx fatal: default action causes potential...
   you have to install `bison' (the GNU version of `yacc').  Normally
you don't have to do this, since *MySQL* comes with an already-compiled
`sql_yacc.cc' file.

   If you are using `gcc' and want to have statically-linked code, use
`LDFLAGS="-static" ./configure ...'

MIT-pthreads notes (FreeBSD)
============================

   On most systems, you can force the usage of MIT-pthreads with the
`configure' switch `--with-mit-threads'.

   Building in a non-source directory is not supported when using
MIT-pthreads, because we want to minimize our changes to this code.

   MIT-pthreads doesn't support the `AF_UNIX' protocol so we must use
the TCP/IP protocol for all connections (which is a little slower).  If
you can't connect to a table, try using the host switch to `mysql'
(`-h' or `--host').  This must be done if you have configured the
distribution using `--without-server' to build only the client code,
because the default connection is to use Unix sockets.

   When *MySQL* is compiled using MIT-pthreads, system locking is
disabled by default for performance reasons. One can start the server
with system locking with the `--use-locking' switch.

   Sometimes (at least on Solaris) the pthread `bind()' command fails
to bind to a socket without any error message. The result is that all
connections to the server fail.

     > mysqladmin ver
     mysqladmin: connect to server at '' failed;
     error: 'Can't connect to mysql server on localhost (146)'

   The solution to this is to kill the `mysqld' daemon and restart it.
This has only happened to us when we have forced the daemon down and
done a restart immediately.

   `sleep()' isn't interruptible with `SIGINT' (break) with
MIT-pthreads. This is only notable in `mysqladmin --sleep'. One must
wait for the end of the `sleep()' before the interrupt is served and
the process stops.

   We haven't gotten `readline' to work with MIT-pthreads. (This isn't
needed, but may be interesting for someone)

   When linking (at least on Solaris) you will receive warning messages
like:

     ld: warning: symbol `_iob' has differing sizes:
     	(file /my/local/pthreads/lib/libpthread.a(findfp.o) value=0x4;
     file /usr/lib/libc.so value=0x140);
     	/my/local/pthreads/lib/libpthread.a(findfp.o) definition taken
     ld: warning: symbol `__iob' has differing sizes:
     	(file /my/local/pthreads/lib/libpthread.a(findfp.o) value=0x4;
     file /usr/lib/libc.so value=0x140);
     	/my/local/pthreads/lib/libpthread.a(findfp.o) definition taken

   Some other warnings which also can be ignored:

     implicit declaration of function `int strtoll(...)'
     implicit declaration of function `int strtoul(...)'

Perl installation comments
==========================

   The included `perl' client code requires perl5.004 or later.

   If you get the following error (from `mysqlperl' or `DBD-mysql'):

     /usr/bin/perl: can't resolve symbol '__moddi3'
     /usr/bin/perl: can't resolve symbol '__divdi3'

   You are probably using `gcc' (or using an old binary compiled with
`gcc'). Add `-L/usr/lib/gcc-lib/... -lgcc' to the link command when the
`mysql.so' library gets built (check the output from `make' for
`mysql.so' when you compile the `perl' client).  `-L/...'  is the path
to the directory where `libgcc.a' exists.  Change it to indicate where
that library actually is located on your system.

   Another problem may be that `perl' and *MySQL* aren't both compiled
with `gcc'.  You can solve this problem by compiling everything with
`gcc'.

   If you want to use the `perl' module on a system that doesn't
support dynamic linking (like SCO) you can always make a static version
of `perl' with DBI and DBD-mysql:

   First you create a statically-linked DBI by doing:
     perl Makefile.PL LINKTYPE=static
     make
     make install
     make perl

   After this you must install the new `perl'. The output of `make
perl' will contain the exact `make' command!  On SCO this is `make -f
Makefile.aperl inst_perl MAP_TARGET=perl'

   Next you create a statically linked DBD::mysql:
     perl Makefile.PL LINKTYPE=static
     make
     make install
     make perl

   You should also install the new `perl' (see the DBI `perl'
installation above).

Special things to consider for some machine/OS combinations
===========================================================

Solaris notes
-------------

   Sun native threads only work on Solaris 2.5 and higher. For 2.4 and
earlier versions, you can use MIT-pthreads. *Note MIT-pthreads::.

   If too many processes try to connect very rapidly to `mysqld' one
will get `Error in accept : Protocol error' in the *MySQL* log.

   If you have the Sun Workshop 4.2 compiler you can configure with:
`CC=cc CFLAGS="-Xa -fast -xstrconst -mt" CXX=CC CXXFLAGS="-xsb -noex
-fast -mt" ./configure'

   You may also have to change the line in `configure' that looks like
this:

   `#if !defined(__STDC__) || __STDC__ != 1' to `#if
!defined(__STDC__)' because if you turn on `__STDC__' with the `-Xc'
switch, the Sun compiler can't compile with the Solaris `pthread.h'
header files anymore. This is a Sun bug (broken compiler or broken
include file).

   If the compiled `mysqld' gives a error like: `libc internal error:
_rmutex_unlock: rmutex not held' you have tried to compile *MySQL* with
the Sun compiler without enabling the multi-thread switch `-mt'. Add
`-mt' to `CFLAGS' and `CXXFLAGS' and try again.

   If you get the following error when compiling *MySQL* with `gcc':

     gcc -O3 -g -O2 -DDBUG_OFF  -o thr_alarm ...
     ./thr_alarm.c: In function `signal_hand':
     ./thr_alarm.c:556: too many arguments to function `sigwait'

   This means that your `gcc' is not configured for your version of
Solaris!  The proper thing to do in this case is to get the newest
version of `egcs' or `gcc' and compile it with your current `gcc'
compiler!  At least for Solaris 2.5, almost all binary versions of
`gcc' have old, unusable include files that will break all programs
that use threads (and possibly other programs!)

   Solaris `tar' can't handle long file names;  You may get the
following error (or something similar) when unpacking the *MySQL*
distribution:

     x mysql-3.21.21a-beta-sun-solaris2.6-sparc/perl/Mysql-modules/blib/lib/auto/Msql-Mysql-modules, 0 bytes, 0 tape blocks
     tar: directory checksum error

   In this case you have to use GNU `tar' to unpack the distribution.
You can find a precompiled copy of GNU `tar' (`gtar') for Solaris at
`http://www.mysql.com/Downloads/'.

SunOS 4 notes
-------------

   On SunOS 4, MIT-pthreads is needed. You must have GNU `make' to
compile (because of MIT-pthreads).

   In `readline' you may get warnings about duplicate defines. These
may be ignored.

   When compiling `mysqld' there will be some warnings about `implicit
declaration of function'. These may be ignored.

Linux notes for all versions
----------------------------

   On Linux you should use the `--skip-locking' flag to `mysqld' if you
start it yourself. Normally the demon is started by `safe_mysqld' and
the flag is added automatically. This flag is needed due to a bug in
Linux file locking calls. This bug is known to exist as recently as
Linux version 2.0.33.

   If you can't start `mysqld' or if `mysql_install_db' doesn't work,
please continue reading!  This only happens on Linux system with
problems in the LinuxThreads or libc/glibc libraries. There are a lot
of simple workarounds to get *MySQL* to work!  The simplest is to use
the binary version of *MySQL* (not the RPM) for Linux x86; One nice
aspect of this version is that it's probably 10% faster than any version
you would compile yourself!  *Note Compile and link options::.

   When using LinuxThreads you will see a minimum of three processes
running. These are in fact threads. There will be one thread for the
LinuxThreads manager, one thread to handle connections, and one thread
to handle alarms and signals.

   if you are using RedHat you might get errors like:

     /usr/bin/perl is needed...
     /usr/sh is needed...
     /usr/sh is needed...

   If so, upgrade `rpm' itself to `rpm-2.4.11-1.i386.rpm' &
`rpm-devel-2.4.11-1.i386.rpm' (or later versions).

   You can get the 4.2 updates from
`ftp://ftp.redhat.com/updates/4.2/i386'. Or
`http://www.sunsite.unc.edu/pub/Linux/distributions/redhat/code/rpm/'
for other distributions.

Linux-x86 notes.
................

   LinuxThreads should be installed before configuring *MySQL*!

   *MySQL* requires libc version 5.4.12 or newer. glibc version 2.0.6
and later should also work. There have been some problems with the
glibc RPMs from RedHat so if you have problems, check whether or not
there are any updates!

   On some older Linux distributions `configure' may produce an error
like: `Syntax error in sched.h. Change _P to __P in the
/usr/include/sched.h file.\  See the Installation chapter in the
Reference Manual'. Just do what the error message says and add an extra
underscore to the `_P' macro that only has one underscore. Then try
again.

   You may get some warnings when compiling (these can be ignored):

     mysqld.cc -o objs-thread/mysqld.o
     mysqld.cc: In function `void init_signals()':
     mysqld.cc:315: warning: assignment of negative value `-1' to `long unsigned int'
     mysqld.cc: In function `void * signal_hand(void *)':
     mysqld.cc:346: warning: assignment of negative value `-1' to `long unsigned int'

   In Debian GNU/Linux, if you want *MySQL* to start automatically when
the system boots, do the following:

     > cp scripts/mysql.server /etc/init.d/mysql.server
     > /usr/sbin/update-rc.d mysql.server defaults 99

   If `mysqld' always core dumps when starting, the problem may be that
you have an old `/lib/libc.a'.  Try renaming this, remove `sql/mysqld'
and do a new `make install' and try again.  This problem has been
reported on some Slackware installations. RedHat 5.0 has also a similar
problem with some new glibc versions. More about this later.

RedHat 5.0
..........

   If you install all the official RedHat patches (including
glibc-2.0.6-9 and glibc-devel-2.0.6-9) *MySQL* should work out of the
box (see above for how to configure).

   The updates are needed since there is a bug in glibc 2.0.5 in how
`pthread_key_create' variables are freed. With glibc 2.0.5 you must use
the statically-linked *MySQL* binary distribution. If you want to
compile from source you must install the corrected version of
LinuxThreads from `http://www.tcx.se/Downloads/Linux' or upgrade your
glibc.

   If you have an incorrect glibc or LinuxThreads version the symptom
is that `mysqld' crashes after each connection. For example,
`mysqladmin version' will crash `mysqld' when it finishes!

   Another symptom of incorrect libraries is that `mysqld' crashes at
once when it starts. One some Linux systems this can be fixed by
configuring with `LDFLAGS=-static ./configure'.  On some RedHat 5.0
system it will only work WITHOUT `LDFLAGS=-static'.  This is known to
happen even with versions of glibc as new as 2.0.7-4!

   For the source distribution of glibc 2.0.7 you can find a patch at
`http://www.tcx.se/Download/Linux/glibc-2.0.7-total-patch.tgz' that is
easy to apply and is tested with `MySQL'!

   If you experience crashes like these when you build *MySQL*, you can
always download the newest binary version of *MySQL*.  This is
statically-linked to avoid library conflicts and should work on all
Linux systems!

   If you want to compile this yourself, check how to debug `mysqld'!
*MySQL* comes with an internal debugger, so it's very easy to get a
trace file that probably will help solve your problem very quickly!
*Note Debugging::.

Linux-Sparc notes.
..................

   In some implementations `readdir_r' is broken.  The symptom is that
`SHOW DATABASES' always returns an empty set.  This can be fixed by
removing `HAVE_READDIR_R' from `config.h'.

   Some problems will require patching your Linux installation.  The
patch can be found at
`http://www.tcx.se/patches/Linux-sparc-2.0.30.diff'. This patch is
against the Linux distribution `sparclinux-2.0.30.tar.gz', that is
available at `vger.rutgers.edu'.  This is a version of Linux which was
never merged with the official 2.0.30.  You must also install
LinuxThreads 0.6 or newer.

   Thanks to <jacques@solucorp.qc.ca> for the above information.

Linux-Alpha notes.
..................

   The first problem is LinuxThreads.  You must patch LinuxThreads for
Alpha because the RedHat distribution uses an old (broken) LinuxThreads
version.

  1. Obtain the glibc2.5c source from any GNU FTP site.

  2. Get the file



     `ftp://www.tcx.se/pub/mysql/linux/patched-glibc-linuxthreads-0.6.tgz'.
     This includes a fixed `.c' file.  Copy this to the glibc
     `./linuxthreads' directory.

  3. Configure and compile glibc (You have to read the manual how to do
     this together with LinuxThreads). Don't install this!

  4. Rename your old version of `/usr/lib/libpthread.a' to
     `/usr/lib/libpthread.a-old'.

  5. Copy the file `glibc.../linuxthreads/libpthread.a' to `/usr/lib'.

  6. Configure *MySQL* with the following command (everything on one
     row):
          CC=gcc CCFLAGS="-Dalpha_linux_port" CXX=gcc CXXFLAGS="-O3 -Dalpha_linux_port" ./configure --prefix=/usr/local/mysql

  7. Try to compile `mysys/thr_lock' and `mysys/thr_alarm'.  Test that
     these work!

  8. Recompile `mysqld'.

   Note that Alpha-Linux is still an alpha platform for *MySQL*.  With
RedHat 5.0 and the patched LinuxThreads you have a very good chance of
it working.

Alpha-DEC-Unix notes
--------------------

   When compiling threaded programs under Digital UNIX using `CC' /
`CXX' the documentation recommends the `-lpthread' switch to `cc' and
`cxx' and the libraries `-lmach -lexc' (in addition to `-lpthread').

   So you have to configure with something like this:

   `CC="cc -pthread" CXX="cxx -pthread -O" ./configure
-with-named-thread-libs="-lpthread -lmach -lexc -lc"'

   When compiling `mysqld' you may see this warning for `mysqld' for a
couple of lines:

     mysqld.cc: In function void handle_connections()':
     mysqld.cc:626: passing long unsigned int *' as argument 3 of accept(int,sockad
     ddr *, int *)'

   You can safely ignore these. This is because `configure' can't detect
warnings, only errors.

   You may get problems with the server exiting if you start it directly
from the command line. If so, try starting it with `nohup safe_mysqld
[options]'.

   `nohup' is a command that ignores any `SIGHUP' sent from the
terminal.

Alpha-DEC-OSF1 notes
--------------------

   If you have problems compiling and have DEC `CC' and `gcc' installed
you can try the following compile line (with `sh' or `bash'):

     CC=cc CFLAGS=-O CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql

   On OSF1 V4.0D and compiler "DEC C V5.6-071 on Digital UNIX V4.0
(Rev. 878)" the compiler had some strange behaviour (One gets undefined
`asm' symbols).  `/bin/ld' also appears to be broken (one gets `_exit
undefined' when linking `mysqld').  On this we have managed to compile
*MySQL* with the following `configure' line, after replacing `/bin/ld'
with the version from OSF 4.0C:

     CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql

   In some versions of OSF1, the `alloca()' function is broken. Fix
this by removing `'HAVE_ALLOCA'' from `config.h'.

   The `alloca()' function also may have an incorrect prototype in
`/usr/include/alloca.h'.  This warning resulting from this can be
ignored.

   `configure' automatically will use the following thread libraries:
`-with-named-thread-libs="-lpthread -lmach -lexc -lc"'.

   When using `gcc' you can also try using:

     CFLAGS=-D_PTHREAD_USE_D4 CXX=gcc CXXFLAGS=-O3 ./configure ....

SGI-IRIX notes
--------------

   You may have to undefine some things in `config.h' (generated by
`./configure').

   In some Irix implementations the `alloca()' function is broken. If
the `mysqld' server dies on some `SELECT' statements, remove
`HAVE_ALLOC' & `HAVE_ALLOCA_H' from `config.h'.  If `mysqladmin create'
doesn't work, remove `HAVE_READDIR_R' from `config.h'. You may have to
remove `HAVE_TERM_H' as well.

   Irix 6.2 doesn't support POSIX threads out of of the box.  You must
install these patches, which are available from SGI if you have support:

   1403, 1404, 1644, 1717, 1918, 2000, 2044

   If you get the something like the following error when compiling
`mysql.cc':

     "/usr/include/curses.h", line 82: error(1084): invalid combination of type

   Type the following in the *MySQL* installation directory:

     > extra/replace bool curses_bool < /usr/include/curses.h > include/curses.h
     > make

   There have also been reports about scheduling problems.  If only one
thread is running, things go slow. Avoid this by starting another
client. This may lead to a 2-10 fold increase in execution speed
thereafter for the other thread.

   This is a poorly-understood problem with IRIS threads, so you may
have to improvise to find solutions until this can be fixed.

   If you are compiling with `gcc', you can use the following
`configure' command:

     CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql --with-thread-safe-client

FreeBSD notes
-------------

   If you get an error on `make install' that it can't find
`/usr/include/pthreads', `configure' didn't detect that one needs
MIT-pthreads on FreeBSD. This is fixed by doing:

     rm config.cache
     ./configure --with-mit-threads

   If you get link errors when compiling `mysqlperl' (such as
`ient.a(my_getwd.o): RRS text relocation at 0x9a9f for "__db_pargs_"')

   You must recompile the Perl code with `-DPIC -fpic'.

   Do the following:

  1. First install everything.

  2. Change the line in `client/Makefile' that says `CFLAGS = -g -O2' to
     `CFLAGS = -O2 -DPIC -fpic'

  3. `cd client'

  4. `rm *.o'

  5. `make libmysqlclient.a'

  6. `cd ../perl'

  7. `make'

   This shall be handled automatically in the future, we hope.

   The FreeBSD `make' behaviour is slightly different from that of GNU
`make'. If you have a problem that `perl/Makefile' doesn't get
generated, you should install GNU `make'.

   If `mysql' or `mysqladmin' takes a long time to respond, a user said
the following:

   Are you running the `ppp' user process? On one FreeBSD box (2.2.5)
*MySQL* clients takes a couple of seconds to connect to `mysqld' if the
`ppp' process is running.

   FreeBSD is also known to have a very low default file handle limit.
*Note Not enough file handles::.

   If you have a problem that `SELECT NOW()' returns GMT and not your
local time, you have to set the `TZ' environment variable to your
current timezone.

   Make sure that you modify the `/etc/hosts' file so that the
`localhost'  entry is correct (otherwise you will have problems
connecting to the database).

   If you are using FreeBSD 2.2.6:

   Don't forget to apply the ttcp and mmap-22 patches to the OS (for
security reasons).  Please see `http://www.freebsd.org' for these CERT
patches.

FreeBSD-3.0 notes.
..................

   You have to run `configure' with:

   `--with-named-thread-libs=-lc_r'

   The pthreads library for FreeBSD doesn't contain the `sigwait'
function and there are some bugs in it.  To fix this, get the
`FreeBSD-3.0-libc_r-1.0.diff' file and apply this in the
`/usr/src/lib/libc_r/uthread' directory. Then follow the instructions
that can be found with `man pthread' about how to recompile the
`libc_r' library.

   You can test if you have a 'modern' `libpthread.a' with:

     > nm /usr/lib/libc_r.a | grep sigwait

   If the above doesn't find `sigwait' you have to use the above patch
and recompile `libc_r'.

BSD/OS 2.# notes
----------------

   From Jan Legenhausen <jleg@csl-gmbh.net>:

   I finally got `mysqlperl' working on BSDI2.1.

   What I did was almost nothing:
  1. `cd client'

  2. Leave the `Makefile' as it is! (I use `GCC="shlicc2"' per default;
     `perl5' automagically uses `shlicc2' - you should use _one_
     version (either `gcc' or `shlicc2') for both `Mysql.c' and
     `libmysqlclient.a'!)

  3. `rm *.o'

  4. `gmake libmysqlclient.a'

  5. `cd ../perl/mysqlperl'

  6. `make clean'

  7. add `$sysliblist=" -L$tmp -lgcc -lcompat";' to `Makefile.PL', line
     45 (just to be sure - I didn't check if one could leave out this
     one)

  8. `perl Makefile.PL'

  9. remove all old `libmysqlclient.a''s in `/usr/lib' and
     `/usr/contrib/lib'

 10. `make install'

   If you get the following error when compiling *MySQL*:

     item_func.h: In method `Item_func_ge::Item_func_ge(const Item_func_ge &)':
     item_func.h:28: virtual memory exhausted
     make[2]: *** [item_func.o] Error 1

   Then your ulimit for virtual memory is too low. Try using: `ulimit
-v 80000' and do `make' again.

   If you are using `gcc' you can also add the flag `-fno-inline' to
the compile line when compiling `sql_yacc.cc'.

   If you have a problem that `SELECT NOW()' returns GMT and not your
local time, you have to set the `TZ' environment variable to your
current timezone.

BSD/OS 3.# notes.
.................

  1. Upgrade to BSD/OS 3.1. If that is not possible, install BSDIpatch
     M300-038.

  2. Use the following configuration command when installing *MySQL*
     (all on one line):
          env CXX=shlicc++ CC=shlicc2 ./configure --prefix=/usr/local/mysql
          --localstatedir=/var/mysql --without-perl
          --with-unix-socket-path=/var/mysql/mysql.sock
     The following is also known to work (again, all on one line):
          env CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql
          --with-unix-socket-path=/var/mysql/mysql.sock

  3. If you have problems with performance under heavy load, try using
     the `--skip-thread-prior' switch to `safe_mysqld'!  This will run
     all threads with the same priority and on BSDI 3.1 this gives
     better performance.  (At least until BSDI fixes their thread
     scheduler).

   You can change the directory locations if you wish, or just use their
defaults by not specifying them.

SCO notes
---------

   The current port is only tested on a 'sco3.2v5.0.4' system.  There
has also been a lot of progress on a port to 'sco 3.2v4.2'.

  1. For OpenServer 5.0.X You need to use GDS in Skunkware 95 (95q4c).
     This is necessary because GNU `gcc' 2.7.2 in Skunkware 97 does not
     have GNU `as'.

  2. You need the port of GCC 2.5.? for this product and the Development
     system.  They are required on this version of SCO UNIX.  You cannot
     just use the GCC Dev system.

  3. One should get FSU thread package and install this first.  This
     can be found at:
     `http://www.cs.wustl.edu/~schmidt/ACE_wrappers/FSU-threads.tar.gz'.
     You can also get a precompiled package from:
     `ftp://www.tcx.se/pub/mysql/Downloads/SCO/FSU-threads-3.5c.tar.gz'.

  4. FSU pthreads can be compiled with SCO UNIX 4.2 with tcpip.  Or
     OpenServer 3.0 or Open Desktop 3.0 (OS 3.0 ODT 3.0), with the SCO
     Development System installed using a good port of GCC 2.5.X ODT or
     OS 3.0 you will need a good port of GCC 2.5.? There are a lot of
     problems without a good port.  The port for this product requires
     the SCO UNIX Development system.  Without it, you are missing the
     libraries and the linker that is needed.

  5. To build FSU pthreads in your system do the following:
       1. Run `./configure' in the `threads/src' directory and select
          the SCO OpenServer option. This command copies
          `Makefile.SCO5' to `Makefile'.

       2. Run `make'.

       3. To install in the default `/usr/include' directory, login as
          root and `cd' to `thread/src' directory, and run `make
          install'.

  6. Remember to use GNU `make' when making *MySQL*.

  7. If you don't start `safe_mysqld' as root, you will probably only
     get the default 110 open files per process.  `mysqld' will write a
     note about this in the log file.

  8. With SCO 3.2V4.2 you must use a FSU-pthreads version 3.5c or newer.
     The following `configure' command should work (all on one line):
          CFLAGS="-D_XOPEN_XPG4" CXX=gcc CXXFLAGS="-D_XOPEN_XPG4" ./configure
          --with-debug=yes --prefix=/usr/local/mysql
          --with-named-thread-libs="-lgthreads -lsocket -lgen -lgthreads"
          --with-named-curses-libs="-lcurses"
          --without-perl
     You may get some problems with some include files. In this case
     you can find new SCO specific include files at:





     `ftp://www.tcx.se/pub/mysql/Downloads/SCO/SCO-3.2v4.2-includes.tar.gz'.
     You should unpack this in the `mysql-source-distributions/include'
     directory!

   SCO development notes:

   * *MySQL* should automatically detect FSU-threads and link `mysqld'
     with `-lgthreads -lsocket -lgthreads'.

   * The SCO development libraries are reentrant in FSU pthreads. SCO
     claims that its libraries function are reentrant so they must be
     reentrant with FSU pthreads. FSU pthreads on OpenServer tries to
     use the SCO scheme to make reentrant library.

   * FSU threads (at least the version at `www.tcx.se') comes linked
     with GNU `malloc'.  If you get problems with memory usage, check
     that `gmalloc.o' is included in `libgthreads.a' and
     `libgthreads.so'.

   * In FSU pthreads, the following system calls are pthreads aware:
     `read', `write', `getmsg', `connect', `accept', `select' and
     `wait'.

IBM-AIX notes
-------------

   When using the IBM compiler, something like this is needed:

     CC="xlc_r -ma -O3 -qstrict" CXX="xlC_r -ma -O3 -qstrict" ./configure

   Automatic detection of `xlC' is missing from `autoconf'.

HP-UX notes
-----------

   There are a couple of 'small' problems when compiling *MySQL* on
HP-UX.  Below we describe some problems and workarounds when using the
HP-UX compiler and `gcc' 2.8.0.

   `gcc' 2.8.0 can't compile `readline' on HP-UX (an internal compiler
error occurs).  MIT-pthreads can't be compiled with HP-UX compiler,
because it can't compile `.S' (assembler) files.

   We got *MySQL* to compile on HP-UX 10.20 by doing the following:
     CC=cc CFLAGS="+z +e -Dhp9000s800 -D__hpux__" CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql --with-low-memory
     cd mit-pthreads
     rm config.cache
     CC=gcc CXX=gcc ./configure
     cd ..
     make
     make install
     scripts/mysql_install_db

   This compiles *MySQL* with the HP-UX compiler, except for the
MIT-pthreads part of the distribution, which is compiled with `gcc'.

TCX binaries
============

   As a service TCX provides a set of binary distributions of *MySQL*
that are compiled at TCX or at sites where customers kindly have given
us access to their machines.

   These distributions are generated with
`scripts/make_binary_distribution' and are configured with the
following compilers and options.

SunOS 4.1.4 2  gcc 2.7.2.1    CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure     
sun4c                         -prefix=/usr/local/mysql                    
SunOS 5.5.1    egcs 1.0.3a    CC=gcc CFLAGS="-O6 -fomit-frame-pointer"    
sun4u                         CXX=gcc CXXFLAGS="-O6 -fomit-frame-pointer  
                              -felide-constructors -fno-exceptions        
                              -fno-rtti" ./configure                      
                              -prefix=/usr/local/mysql -with-low-memory   
SunOS 5.6      egcs 2.90.27   CC=gcc CFLAGS="-O6 -fomit-frame-pointer"    
sun4u                         CXX=gcc CXXFLAGS="-O6 -fomit-frame-pointer  
                              -felide-constructors -fno-exceptions        
                              -fno-rtti" ./configure                      
                              -prefix=/usr/local/mysql -with-low-memory   
SunOS 5.6      gcc 2.8.1      CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure     
i86pc                         -prefix=/usr/local/mysql -with-low-memory   
Linux 2.0.33   pgcc-2.90.29   CFLAGS="-O6 -mpentium -mstack-align-double  
i386           (egcs 1.0.3a)  -fomit-frame-pointer" CXX=gcc               
                              CXXFLAGS="-O6 -mpentium                     
                              -mstack-align-double -fomit-frame-pointer   
                              -felide-constructors  -fno-exceptions       
                              -fno-rtti LDFLAGS=-static ./configure       
                              -prefix=/usr/local/mysql -enable-assembler  
SCO 3.2v5.0.4  gcc 2.7-95q4   CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure     
i386                          -prefix=/usr/local/mysql                    
AIX 2 4        gcc 2.7.2.2    CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure     
                              -prefix=/usr/local/mysql                    
OSF1 V4.0 564  gcc 2.8.1      CC=gcc CFLAGS=-O CXX=gcc CXXFLAGS=-O3       
alpha                         ./configure -prefix=/usr/local/mysql        
                              -with-low-memory                            
IRIX 6.3 IP32  gcc 2.8.0      CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure     
                              -prefix=/usr/local/mysql                    
BSDI BSD/OS    gcc 2.7.2.1    CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure     
3.1 i386                      -prefix=/usr/local/mysql                    
BSDI BSD/OS    gcc 2.7.2      CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure     
2.1 i386                      -prefix=/usr/local/mysql                    

   Anyone who has more optimal switches for any of the above
configurations can always mail us at <mysql-developer@tcx.se> about
this.

   The RPM distributions are user-contributed distributions.

Win32 notes
===========

   The *MySQL*-win32 version has by now proven itself to be very
stable. The *MySQL*-win32 version has the same features as the
corresponding Unix version of *MySQL* with the following exceptions:

`ALTER TABLE'
     One can't do an `ALTER TABLE' on a file if it is hdld open by
     another thread or the table cache.  On *MySQL*-win32 I have added
     code to close the file owned by the thread that does `ALTER TABLE'
     but *MySQL* can't yet close the the file descriptors used by other
     threads. We have to do a major recode of the file lock system to
     handle this. For now, when using `ALTER TABLE', one must be sure
     that no other threads are using the table.  One can be sure of
     this by doing a `mysqladmin refresh' before doing an `ALTER TABLE'.

`Increasing the table cache'
     Win32 has only a very limited number of open files it can handle
     at the the same time (about 255). Because of this one shouldn't
     increase the number of open connections or number of cached tables
     very much on Win32.

`Win95 and threads'
     Win95 leaks memory for each thread.  Because of this one shouldn't
     run `mysqld' for an extended time on Win95 if one does many
     connections; each connection in *MySQL* creates a new thread!  NT
     doesn't suffer from this bug.

`Blocking read'
     *MySQL* uses a blocking read for each connection.  For the moment
     this means that 'mysqladmin shutdown' will not take down *MySQL*
     completely before all clients has closed the connection.  We plan
     to fix this in the near future.

   Here is some open issues for someone that may want to help us with
the Win32 release:

*
     When one does a suspend on a laptop running Win95, the `mysqld'
     demon doesn't accept new connections when the laptop is resumed.
     We don't know if this is a problem with Win95, TCP/IP or *MySQL*.

*
     It would also be real nice to be able to kill `mysqld' from the
     task manager.  For the moment one must use `mysqladmin shutdown'.

*
     When registering `mysqld' as a service with `-install' (on NT) it
     would be nice if one could also add default options on the command
     line.

*
     <<<<<<< manual.texi GUI versions of the standard mysql clients
     (mysql, mysqlshow, mysqladmin, and mysqldump would be nice.

*
     Port readline to Win32 for use in the mysql command line tool.
     GUI versions of the standard *MySQL* clients (`mysql',
     `mysqlshow', `mysqladmin', and `mysqldump') would be nice.

*
     It would be nice if the 'read' and 'write' to sockets in `net.c'
     would be interruptible. This would make it possible to kill open
     threads with `mysqladmin kill' on Win32.

*
     Documentation of which windows programs work with
     MySQL-WIN32/MyODBC and what one has to do to get them working.

*
     `mysqld' always starts in the "C" locale and not in the default
     locale.  We would like to have `mysqld' use the current locale for
     the sort order.

*
     Add more options to MysqlManager

*
     Change the communication protocol between the server/client to use
     windows intern communication instead of sockets and TCP/IP.

   Other Win32 specific issues are described in the README file that
comes with the *MySQL*-win32 distribution.

Installation instructions for *MySQL* binary releases
=====================================================

   *Please* always use the `mysqlbug' script when posting questions to
the mailing list (<mysql@tcx.se>). Even if the problem isn't a bug,
`mysqlbug' gathers some system information that will help others solve
your problem! *Note Bug reports::.

  1. Get the distribution. That is a file called something like
     mysql-version-OS.tgz. For example a file holding a *MySQL* version
     3.21.15 for a intel linux machine is called
     `mysql-3.21.15-alpha-pc-linux-gnu-i586.tgz'.

  2.  Pick a directory to put *MySQL* in: In the following we will use
     `/usr/local/mysql' as the installation directory and *MySQL*
     version VERSION (something like 3.21.15) for SunOS5 (Solaris), for
     example.

  3.  All of the following instructions assume you have permission to
     create files in `/usr/local'.

     Use the following commands to create the directory and unpack the
     distribution:

          > cd /usr/local
          > zcat /<where ever you put it>/mysql-3.20.0-SunOS5.tgz | tar xvf -
          > ln -s mysql-VERSION mysql

  4. After this you should install the *MySQL* privilege tables.

     In some binary versions the grant tables may already be created,
     for others distributions you should edit the
     `scripts/mysql_install_db' script to have the privileges you want
     and run it. The default privileges is that anybody may create/use
     the databases named 'test' or starting with "test_". The *MySQL*
     user root can do anything. Note that you do not have to run the
     *MySQL* server as root. Any user is ok as long as it can read and
     write in the installtion directories/files.

     If you want to recreate the privilege tables remove all the *.ISM
     and  *.ISD files in the mysql database directory, edit the
     scripts/mysql_install_db script to have the privileges you want
     and run it.

     This creates the privilege tables if they don't exist:
          > scripts/mysql_install_db

     *Note mysql_install_db::

     If you want to change things in the grant tables after installing
     you should use `mysql -u root mysql' to connect to the grant tables
     as the 'root' user.

     The `mysql_install_db' script also starts the `mysqld' daemon.

  5. Normally, start the *MySQL* server daemon (not needed the first
     time):

          > bin/safe_mysqld --log &

  6. You can test that the daemon is running by doing this:

          > bin/mysqladmin ver

     That should print something like this. The exact output depends on
     you platfrom and use.
          bin/mysqladmin  Ver 6.3 Distrib 3.21.15-alpha, for SOLARIS 2.5 on SPARCstation
          TCX Datakonsult AB, by Monty
          
          Server version          3.21.15-alpha
          Protocol version        9
          Connection              Localhost via UNIX socket
          TCP port                3306
          UNIX socket             /tmp/mysql.sock
          Uptime:                 2 days 1 hour 42 min 3 sec
          
          Running threads: 2  Questions: 450378  Reloads: 17  Open tables: 64

To get perl work do the following:
----------------------------------

     cd perl/DBI
     perl Makefile.PL
     make
     make install
     cd ../Mysql-modules
     perl Makefile.PL
     make
     make install

   You should use the `safe_mysqld' script to the server.
`safe_mysqld' expects one of two conditions to be true:

  1. You're executing the script from the base mysql installation
     directory (for example `/usr/local/mysql')

  2. The server should reside in `/my/'.  To get it to run correctly,
     you should cd to `/usr/local/mysql' and then execute `safe_mysqld'
     or modify the script so that it expects the base mysql directory
     to be `/usr/local/mysql' rather than the default `/my/'.

   When you execute this:

     > bin/mysqld --help

   You will get the options for mysqld (and safe_mysqld) and the current
paths. Normally you only should need to change the `--basedir=path'.
You can test the path switches by executing:

     > bin/mysqld --basedir=/usr/local --help

   If you would like to use mysqlaccess and have the mysql distribution
in some nonstandard place, you must change the path to mysql in
mysqlaccess. `bin/mysqlaccess' about line 308:

     $MYSQL = '/usr/local/bin/mysql --batch --unbuffered';

   If you don't change the path, you will get a 'broken pipe' error when
using mysqlaccess.

   If you would like *MySQL* to start when you boot your machine, you
can copy `bin/mysql.server' to where your system has it startup files.
More information can be bound in the bin/mysql.server script itself.

Linux notes
-----------

   * *MySQL* needs at least Linux 2.0.

   * The binary release is linked with -static, which means that you
     don't have to worry about which version of your system libraries.
     You don't have to install LinuxThreads either.  A program linked
     with -static is slightly bigger but also slighty faster (3-5%)
     than a dynamically linked program. The only problem is that you
     can't use UDF (user definable functions) with a -static program.
     If you are going to write or use UDF functions (this is only
     something for C or C++ programmers) you have to compile *MySQL*
     yourself.

   * The Linux-intel binary release of *MySQL* is configured for the
     highest possible speed (we are even using the pentium compiler,
     pgcc):
          CC=gcc
          CFLAGS="-O6 -mpentium -mstack-align-double -fomit-frame-pointer"
          CXX=gcc
          CXXFLAGS=-O6 -mpentium -mstack-align-double -fomit-frame-pointer -felide-constructors"
          LDFLAGS=-static
          ./configure --prefix=/usr/local/mysql -enable-assembler

     All of the above is typed as one long line!

   * The perl distribution needs perl5.004.03 or newer.

HP-UX notes
-----------

   The binary distribution of *MySQL* for HP-UX is distributed as an HP
depot file.  This means that you must be running at least HP-UX 10.x to
have access to HP's software depot tools.

   This version of *MySQL* was compiled on an HP 9000/8xx server under
HP-UX 10.20, and uses MIT Pthreads. It is known to work well under this
configuration. This version does *not* use HP's native thread package.
It is highly unlikely that *MySQL* will use HP native threads on
anything but HP-UX 10.30 or later.

   Other configurations that may work:

   9000/7xx - HP-UX 10.20+ 9000/8xx - HP-UX 10.30 (does not use HP
native threads)

   The following configurations almost definitely won't work:

   9000/7xx or 8xx - HP-UX 10.x where x < 2 9000/7xx or 8xx - HP-UX 9.x

   To install (everything, including server, client and development
tools):

   /usr/sbin/swinstall -s <full path to the depot file> mysql.full

   To install server only:

   /usr/sbin/swinstall -s <full path to the depot file> mysql.server

   To install client pack only:

   /usr/sbin/swinstall -s <full path to the depot file> mysql.client

   To install development tools only:

   /usr/sbin/swinstall -s <full path to the depot file> mysql.developer

   The depot will place binaries/libraries in /opt/mysql and data in
/var/opt/mysql. The depot will also create the appropriate entries in
/sbin/init.d and /sbin/rc2.d to automatically start the server on boot.
This obviously entails being root to install.

Linking client libraries
------------------------

   Clients have to be linked with: `-lmysqlclient'

Problems running mysql_install_db
=================================

   The default privileges is that anybody may create/use the databases
named `test' or starting with `test_'. `root' can do anyting. *Note
Privileges::.

   To change the defaults edit the script before running it.  If this is
the first time you install *MySQL* you must run this command. If you
don't do it you will get the error: `Can't find file:
'./mysql/host.frm''. This script also starts the mysqld daemon the first
time.

   If you want to change things in the grant tables after installing you
should use `mysql -u root mysql' to connect to the grant tables as the
'root' user.

   Normal start of the *MySQL* server daemon (not needed the first
time): `'installation_directory'/bin/safe_mysqld --log'

   It may happen that `mysql_install_db' doesn't install the privilege
tables but ends with:

     Starting mysql server
     starting mysqld demon with databases from xxxxxx
     mysql demon ended

   In this case you should examine the log in the xxxxxx directory very
carefully!  This contains the reason why mysqld didn't start.  If you
can't understand what happens, you should at least include the log when
you post a bug report using mysqlbug!

   Possible problems when running `mysql_install_db' are:

`There is already a mysqld deamon running.'
     In this case you have probably don't have to run mysql_install_db
     at all.  One only have to run mysql_install_db once when one
     install *MySQL* the first time.

`Installing a second mysqld daemon doesn't work when one daemon is running.'
     The problem is the new server tries to use the same socket and
     port as the old one.  You can start the new server with a
     different socket and port as follows:

          MYSQL_UNIX_PORT=/tmp/mysqld-new.sock
          MYSQL_TCP_PORT=3307
          export MYSQL_UNIX_PORT MYSQL_TCP_PORT
          scripts/mysql_install_db

     After this you should edit your server boot script to start both
     daemon with different sockets and ports (safe_mysqld -socket=...
     -port=....).

`mysqld crashes at once.'
     If you are running RedHat 5.0 and a glibc version before glibc
     2.0.7-5 you should check that you have installed all glibc
     patches!  There is a lot of information about this in the `MySQL'
     mail archives.  *Note Linux::

`Can't connect to the server (when using MIT-pthreads)'
     If `mysql_install_db' can't connect to the server you should check
     that you have an entry in `/etc/hosts' like:

          127.0.0.1		localhost
     The above is only a problem on system that doesn't have a thread
     library and *MySQL* has to use MIT-pthreads.

`You don't have write access to create a socket file (in `/tmp'?)'
     In this case you have to start mysqld manually and add the
     privilege information yourself. If you are using a binary version
     and are not installing in /usr/local/mysql, you have specify the
     paths mysqld should use with arguments.  You can get information
     about which paths mysqld uses and the how to change them with
     `mysqld --help'.  You can also specify paths for safe_mysqld by
     doing the following:

          MYSQL_UNIX_PATH=/some_directory_for_tmp_files/mysqld.sock
          MYSQL_TCP_PORT=3306
          TMPDIR=/some_directory_for_tmp_files/
          export MYSQL_UNIX_PATH MYSQL_TCP_PORT TMPDIR
          
          scripts/mysql_install_db
             or
          bin/mysqld --skip-grant
          
          bin/mysql -u root mysql
     After this you can execute the sql commands in mysql_install_db.

`The paths may be different from what mysqld expects.'
     You can override all paths to mysqld with command line arguments.
     Use `mysqld --help' for more information. You can edit
     bin/safe_mysqld to reflect the paths for your installation.

   A simple test to see that everything is working is: `bin/mysqladmin
version'

Problems starting *MySQL*
=========================

   Check the log file to see if mysqld started up correctly.

   `mysqld' daemon starts with a cd to 'mysql-data-dir'. After this,
mysqld-data-dir is changed to './' (current dir). All paths (databases,
pid file, and log file) have this directory as base path './'. If you
have any problems with wrong paths, try `mysqld --help' to see your
current paths. Every path can be changed by a startup option to
`safe_mysqld' or `mysqld'

     cd <localstatedir default /usr/local/var>
     tail <your host name>.log

   To verify that *MySQL* is working run the following tests:

     > cd /usr/local/bin
     > ./mysqlshow
     +-----------+
     | Databases |
     +-----------+
     | mysql     |
     +-----------+
     
     > ./mysqlshow mysql
     Database: mysql
     +--------+
     | Tables |
     +--------+
     | db     |
     | host   |
     | user   |
     +--------+
     
     > ./mysql -e "select host,db,user from db" mysql
     +------+--------+------+
     | host | db     | user |
     +------+--------+------+
     | %    | test   |      |
     | %    | test_% |      |
     +------+--------+------+

   There is also a benchmark suite so you can compare how *MySQL*
performs on different platforms. In the near future this will also be
used to compare *MySQL* to other SQL databases.

     > cd bench
     > run-auto-increment-test

   You can also run the tests in the test subdirectory. To run
`auto_increment.tst':

     ./mysql -vf test < ./tests/auto_increment.tst

   Expected results are shown in the file `./tests/auto_increment.res'.

   The safe_mysqld script is written that it should be able to start a
source and a binary version of mysqld, even if these have sligtly
different paths!

   You can install a binary release of *MySQL* anywhere as long as you
start safe_mysqld from installation directory:

     cd mysql_installation_directory
     bin/safe_mysqld &

   If you want to change the startup options to mysqld you can always
edit safe_mysqld!  In this case you should copy safe_mysqld to some
other location that it will not be overwritten if you decide to upgrade
*MySQL* sometime!

Automatic start/stop of *MySQL*
===============================

   To start or stop *MySQL* use the following commands:

     scripts/mysql.server stop
     scripts/mysql.server start

   You might want to add these start and stop commands in the
appropriate places in your `/etc/rc*' files when you start using *MySQL*
for production applications.  You can edit the mysql.server script to
start safe_mysqld from some specific location and as some specific
user. You can also add startup options to mysqld here.

Option files
============

   *MySQL* 3.22 can read default startup options for the server and
clients from options files.

   *MySQL* reads default options from the following places on Unix:

/etc/my.cnf            Global options.                                    
/mysql-data-dir/my.cnf Server specific options.                           
~/.my.cnf              User specific options.                             

   Note the that 'mysql-data-dir' in the above is the directory that is
specified compiled time! (Note the one specified with -data)

   *MySQL* reads default option from the following places on Win32:

C:\my.cnf              Global options.                                    
C:\mysql\data\my.cnf   Server specific options.                           

   The same option in a later file overrides the same option in a
earlier file.  Command line options overrides file options.

   The following programs supports options files:

   mysql, mysqladmin, mysqld, mysqldump, mysqlimport, isamchk and
pack_isam.

   One can in the options file use all long options that a program
supports!  Run the program with -help to get a list of available
options.

   A option file can contain lines with the following syntaxes:

#comment               Comment lines starts with '#' or ';'. Empty lines  
                       are ignored                                        
[group]                'group' is the name of the program or group for    
                       which one wants to set options.                    
option                 Same as -option on the command line                
option=value           Same as -option=value on the command line          

   Note that for options and values all pre- and end blanks are
automatically deleted.  You may use the escape sequences: \b \t \n \r
\\ and \s (\s  == blank) in your value string.

   If you want to set a mysqld variable you have to use the syntax:
`set-variable = variable=value'.  This corresponds to the command line
option "-set-variable variable=value".

   You will find a sample my.cnf file in the bin or scripts directory
named as my-example.cnf You can copy this to your home directory to
experiment with this.

   There are some predefined groups:

client         Options will be used for all *MySQL* clients (not          
               mysqld). This is the perfect group to use if one wants to  
               save one passwords in the option file.                     

   Here is a typical global option file:

     [client]
     port=3306
     socket=/tmp/mysql.sock
     
     [mysqld]
     port=3306
     socket=/tmp/mysql.sock
     set-variable = key_buffer=16M
     set-variable = max_allowed_packet=1M
     
     [mysqldump]
     quick

   Here is typical user option file:

     [client]
     # The following commands will be sent to all standard *MySQL* clients
     password=my_password
     
     [mysql]
     no-auto-rehash

   If one doesn't want to use the options file one can start the
program with: `--no-defaults'.  This *MUST* be the first option to have
any effect!

   Note for developers:  The options files handling is implemented by
simply adding all matching options before any command line arguments.
This works nicely for programs that uses the last option if an option
is used many times. To change a program to use option files one has
only to add two lines to the old programs. Check any of the standard
mysql clients about how to do this.

How standards-compatible is *MySQL*?
************************************

What extensions has *MySQL* to ANSI SQL92?
==========================================

   The following are useful extensions in *MySQL* that you probably
will not find in other SQL databases.  Be warned that if you use them,
your code will not be portable to other SQL servers.

   * The field types `MEDIUMINT', `SET', `ENUM' and the different
     `BLOB' and `TEXT' types.

   * The field attributes `AUTO_INCREMENT', `BINARY', `UNSIGNED' and
     `ZEROFILL'.

   * All string comparisons are by default are case independent with
     case according to ISO-8859-1 Latin1.  If you don't like this you
     should declare your strings with the `BINARY' attribute.

   * *MySQL* maps all tables to filenames and with *MySQL* one can use
     standard system tools to backup, rename, move, delete and copy
     tables.  This forces *MySQL* to be case sensitive on table names
     on operating systems that have case sensitive filenames (like most
     Unix systems). If you have a problem remembering table names,
     create everything in lowercase.

   * LIKE is allowed on numerical columns.

   * Use of `INTO OUTFILE' and `STRAIGHT_JOIN' in a `SELECT' statement.
     *Note Select::.

   * `EXPLAIN SELECT' to get a description on how tables are joined.

   * Use of index names, indexes on a subpart of a field, and use of
     `INDEX' or `KEY' in a `CREATE TABLE' statement. *Note Create
     table::

   * Use of `DROP column' or `CHANGE column' in an `ALTER TABLE'
     statement. *Note Alter table::.

   * Use of `DROP TABLE' with the keywords `IF EXISTS' or with more
     than one table.

   * Use of `LOAD DATA INFILE'. This syntax is in many cases compatible
     with Oracle's `LOAD DATA INFILE'. *Note Load::.

   * Using `"' instead of `'' to enclose strings.

   * Using the escape `\' character.

   * The `SET OPTION' statement. *Note Set option::

   * One doesn't have to have all columns in the `GROUP BY' part.  This
     gives better performance for some very specific, but quite normal
     queries.  *Note Group by functions::

   * To make it easier for a user that comes from different SQL
     environments mysql supports a a lot of aliases for many functions.
     For example all string functions support both the ANSI SQL and the
     ODBC syntax.

   * The `||' and `&&' operators are, in *MySQL*, synonyms for `OR' and
     `AND', like in the C programming language.  Likewise `|' and `&'
     stand for bitwise `OR' and `AND'.  Because of this nice syntax,
     *MySQL* doesn't support the ANSI SQL operator `||' for string
     concatenation, one has to use `CONCAT()' instead. As `CONCAT()'
     takes any number of arguments it's easy to convert use of the `||'
     operator to *MySQL*.

   * Use of any of the following functions or commands:
        * `CREATE DATABASE' or `DROP DATABASE'.  *Note Create database::

        * `%' instead of mod().  `%' is supported for C programmers and
          for compatibility with PostgreSQL.

        * `=', `<>', `<=' ,`<', `>=',`>', `<<', `>>', `AND',`OR', or
          `LIKE' in a column statement

        * `LAST_INSERT_ID'.  *Note mysql_insert_id::

        * `REGEXP' or `NOT REGEXP'.

        * `CONCAT()' or `CHAR()' with one or more than two arguments.
          In *MySQL* the above functions can take any number of
          arguments.

        * `BIT_COUNT()', `ELT()', `FROM_DAYS()', `FORMAT()', `IF()',
          `PASSWORD()', `ENCRYPT()', `PERIOD_ADD()', `PERIOD_DIFF()',
          `TO_DAYS()', or `WEEKDAY()'.

        * Use of `TRIM' to trim substrings. ANSI SQL only supports
          removal of single characters.

        * The `STD()', `BIT_OR' and `BIT_AND' group functions.

        * Use of `MIN()' or `MAX()' as normal functions, not only group
          functions.

        * Use of `REPLACE' instead of `DELETE' + `INSERT'.  *Note
          Replace::

What functionality is missing in *MySQL*?
=========================================

   The following functionality is missing in the current version of
*MySQL*.  For the priority of new extensions you should consult:
The *MySQL* Todo list
(http://www.tcx.se/Manual_split/manual_Todo.html). That is the latest
version of the Todo list in this manual. *Note Todo::.

Sub-selects
-----------

   The following will not work in *MySQL*:

     SELECT * from table WHERE id IN (SELECT id from table2)

   *MySQL* only supports `INSERT ... SELECT...' and `REPLACE ...
SELECT...'. Independent sub-selects will be probably be available in
3.22.0.  One can now use the function `IN()' in other context however.

SELECT INTO TABLE
-----------------

   *MySQL* doesn't yet support `SELECT ... INTO TABLE...'. Currently
*MySQL* only supports `SELECT ... INTO OUTFILE...', which is basically
the same thing..

Transactions
------------

   Transactions are not supported. *MySQL* will shortly support atomic
operations which is like transactions without rollback. With atomic
operations you can make a bunch of insert/select/whatever commands and
be guaranteed that no other thread will interfere. In this context you
won't usually need rollback. Currently you can do this with the help of
the `LOCK TABLES/UNLOCK TABLES' command.  *Note Lock tables::

Triggers
--------

   Triggers are not supported. The planned update language will be able
to handle stored procedures, but without triggers. Triggers usually slow
down everything, even for queries when they aren't needed.

Foreign Keys
------------

   The `FOREIGN KEY' syntax in *MySQL* exists only for compatibility
with other SQL vendors `CREATE TABLE' commands: It doesn't do anything.
The `FOREIGN KEY' syntax without `ON DELETE ..' is mostly used for
documentation purposes. Some ODBC applications may use this to produce
automatic `WHERE' clauses though, but this is usually easy to override.
`FOREIGN KEY' is sometimes used as a constraint check, but this check
is in practice unnecessary if rows are inserted into the tables in the
right order. *MySQL* only supports these commands because some
application require them to exists (but not work!).

   In *MySQL* one can work around the problem that `ON DELETE ...'
isn't implemented by adding the approative `DELETE' statement to the
application when one deletes records from a table that has `FOREIGN
KEY'.  In practice this is as quick (in some case quicker) and much
more portable than using `FOREIGN KEY'.

   Foreign keys are something that makes life very complicated, because
the foreign key definition must be stored in a database and
implementing them would mean that the whole 'nice approach' of using
files that can be moved, copied and removed would be destroyed.

   In the near future we will extend `FOREIGN KEYS' so that at least
the information will be saved and may be retrieved by mysqldump and
ODBC.

Some reasons NOT to use FOREIGN KEYS
....................................

   There are so many problems with the `FOREIGN KEY's that we don't
know where to start.

   * The speed impact will be terrible when `INSERTING' and `UPDATING'
     records and in this case almost all `FOREIGN KEY' checks are
     useless because one usually inserts records in the right tables in
     the right order.

   * There will also be a need to hold locks on many more tables when
     updating one because the side effects can cascade trough the hole
     database. It's MUCH faster to first delete records from one table
     and subsequently delete them from the other tables.

   * One can't restore a table anymore by doing a full delete from the
     table and then restoring all records (from a new source or from a
     backup).

   * If you have foreign keys you can't dump and restore tables without
     doing this in a very specific order.

   * It's very easy to do 'allowed' circular definitions that make the
     tables impossible to recreate with a single create statement, even
     if the definition works and is usable.

   The only nice aspect of foreign key is that it gives ODBC and some
other client programs the ability to see how a table is connected and
use this to show connection diagrams and to help building applicatons.

   *MySQL* will soon store the `FOREIGN KEY' definitions so that a
client can ask and receive an answer how the original connection was
made. The current `.frm' file format does not have any place for it.

Views
-----

   *MySQL* doesn't support views, but this is on the TODO.

- as start of a comment
-----------------------

   Some other SQL databases have `--' as start comment. *MySQL* has `#'
as the start comment character, even if the `mysql' command line tool
removes all lines that starts with `--'.  You can also use the C
comment style `/* this is a comment */' with *MySQL*.  *Note Comments::

   *MySQL* will not support this degenerated comment style because we
have had many problems with automatically generated SQL queries that
have used something like the following code:

     UPDATE table_name SET credit=credit-!payment!

   Where instead of !payment! we automatically insert the value of the
payment.

   What do you think will happen when 'payment' is negative?

   Because 1-1 is legal in SQL, we think is terrible that '-' means
start comment.

   If you have a sql program in a textfile that contains `--' comments
you should use:

     replace " --" " #" < text-file-with-funny-comments.sql | mysql database.
     
     instead of the normal
     
     mysql database < text-file-with-funny-comments.sql

   You can also change the `--' to `#' comments in the command file:

     replace " --" " #" -- text-file-with-funny-comments.sql

   Change them back with:

     replace " #" " --" -- text-file-with-funny-comments.sql

What standards does *MySQL* follow?
===================================

   Entry level SQL92. ODBC level 0-2.

What functions exist only for compatibility?
============================================

   * `GRANT'. *Note Grant:: This always succeeds. You should use the
     *MySQL* privilege tables. *Note Privileges::

   * `CREATE INDEX'. *Note Create Index:: This always succeeds. You
     should create your index with `CREATE TABLE'. *Note Create table::
     You can also use `ALTER TABLE'. *Note Alter table::.

   * `DROP INDEX'. *Note Drop Index:: This always succeeds. You can use
     `ALTER TABLE' to drop indexes. *Note Alter table::.

Limitations of `BLOB' and `TEXT' types
======================================

   If you want to `GROUP BY' or `ORDER BY' on a `BLOB' or `TEXT' field,
you must make the field into a fixed length object. The standard way to
do this is with the `SUBSTRING' functions. If you don't do this only
the first `max_sort_length' (default=1024) will considered when sorting.

     SELECT comment from table order by substring(comment,20);

How to cope without COMMIT-ROLLBACK
===================================

   *MySQL* doesn't support COMMIT-ROLLBACK. The problem with
COMMIT-ROLLBACK is that to handle this efficiently it would require a
completely different table layout than *MySQL* uses today. *MySQL*
would also need extra threads that do automatic cleanups on the tables
and the disk usage would be much higher. This would make *MySQL* about
2-4 times slower than it is today. One of the reasons that *MySQL* is
so much faster than almost all other SQL databases (typical times are
at least 2-3 times faster) is the lack of COMMIT-ROLLBACK.

   For the moment, we are much more for implementing the SQL server
language (someting like stored procedures). With this you would very
seldom really need COMMIT-ROLLBACK. This would also give much better
performance.

   Loops that need transactions can normally be coded with the help of
`LOCK TABLES', and one doesn't need cursors when one can update records
on the fly.

   We have transactions and cursors on the TODO but not quite
prioritised. If it is implemented it will be as a option to `CREATE
TABLE'. That means that COMMIT-ROLLBACK will only work on those tables
and only those tables will be slower.

   We at TcX have a greater need for a real fast database than a 100%
general database. Whenever we find a way to implement these without any
speed loss we will probably do it. For the moment there are many more
important things to do. Check the TODO for how we prioritise things at
the moment. Customers with higher levels of support can alter this, so
things may be reprioritised.

   The current problem is actually `ROLLBACK'. Without `ROLLBACK' you
can do anything with `LOCK TABLES'. To support `ROLLBACK' *MySQL* would
have to be changed to store all old records that were updated and
revert everything back to the starting point if `ROLLBACK' was issued.
For simple cases this isn't that hard to do (the current isamlog could
be used for this), but if one wants to have `ROLLBACK' with
`ALTER/DROP/CREATE TABLE' it would make everything much harder to
implement.

   To avoid using `ROLLBACK' one can do:

  1. `LOCK TABLES ...'

  2. Test conditions.

  3. Update if everything is ok.

  4. `UNLOCK TABLES'

   This is usually much faster, but not always. The only thing this
doesn't handle if someone does a kill on the process.

   One can also use functions to update things in one operation. By
doing all updates relatively and/or only updating those fields that
actually have changed one can get a very efficient application.

   For example, when we are doing updates on some customer information,
we only update the customer data that has changed and only test that
none of the changed data, or data that depends on the changed data, has
changed in the original row. The test for change is done with the
`WHERE' clause in the `UPDATE' statement. If the record wasn't updated
we give the client a message: "Some of the data you have changed has
been changed by another user", and then we show the old row versus the
new row in a window. The user can then decide which version of the
customer record he should use.

   This gives us something like 'column locking' but actually even
better, because we only update some of the columns with relative
information. This means that a typical update statement looks something
like:

     UPDATE tablename SET pay_back=pay_back+'relative change'
     
     UPDATE customer set customer_date='current_date', address='new address',
     phone='new phone', money_he_owes_us=money_he_owes+'new_money' where
     customer_id=id and address='old address' and phone='old phone';

   As you can see, this is very efficient and even if another client has
changed the 'money_he_owes_us' or 'pay_back' amount this will still
work.

   In many cases, users have wanted `ROLLBACK' and/or `LOCK TABLES' to
manage unique identifiers for some tables. This can be handled much
more efficiently by using an `AUTO_INCREMENT' column and the *MySQL*
API function `mysql_insert_id'. *Note mysql_insert_id::

   At TcX we have never had any need for row level locking as we have
always been able to code around it. I know some cases that really need
row locking, but they are very few. If you want to have row level
locking you can do something like:

     UPDATE table_name SET row_flag=1 WHERE id=ID;

   *MySQL* returns `affected rows' = 1 if the row was found and row_flag
wasn't 1 in the original document. On the TODO there is `GET_LOCK' and
`RELEASE_LOCK' for those that want to implement application level
locking.

How do *MySQL* privileges work?
*******************************

   *MySQL* has an advanced but non-standard security/privilege system.

What can the privilege system do?
=================================

   The basic function of the *MySQL* privilege system is to give a
username on a host select, insert, update and delete privileges on a
database.

   Extra functionality includes the ability to have a anonymous user
and give permission to use *MySQL* specific funtions like `LOAD DATA
INFILE'.

   Please note that the user names for a SQL database, like *MySQL*, has
nothing to do with Unix users. As a convenience most *MySQL* clients
tries to log in with the current user name, but this may be changed
with the `--user' switch. This means that you can't in any way make a
database secure without having passwords for all users.

How does the privilege system work?
===================================

   In *MySQL* the combination of host and user is the unique identity.
Don't think of users, think of host+user and everything should be much
clearer.  You can for example have a user named 'Robb' at two different
hosts (with different privileges) in *MySQL* without any conflicts.

   The *MySQL* privilege system makes sure that each user may do
exactly the things that they are supposed to be allowed to do. The
system decides to grant different privileges depending on *which xuser*
connects from *which host* to *which database*.

   You can always test your privileges with the script `mysqlaccess',
which Yves Carlier has provided for the *MySQL* distribution.  *Note
Access denied:: *Note Security::

   All privileges are stored in three tables. `user', `host' and `db'.

   Everything granted in the `user' table is valid for every database
that cannot be found in the `db' table. For this reason, it might be
wise to grant users (apart from superusers) privileges on a
per-database basis only.

   The `host' table is mainly there to maintain a list of "secure"
servers. At TcX `host' contains a list of all machines on the local
network. These are granted all privileges.

   The connecting user's privileges are calculated by the following
algorithm:

  1. First sort the tables by:      Table                Sorted by                                       
     host                 host without wild/hosts with wild/empty hosts   
     db                   host without wild/hosts with wild/empty hosts   
     user                 host/user                                       



     Host by putting hosts without wildcards first, followed by hosts
     with wildcards and entries with `host = ""'. Within each host,
     sort by user using the same rules. Finally, in the `db' table,
     sort by db using the same rules. In the steps below, we will look
     through the sorted tables and *always use the first match found*.

  2. Get the privileges for the connecting user from the `user' table
     using the first match found.

     Call this set of privileges PRIV.

  3. Get the privileges for the connecting user from the `db' table
     using the first match found.

  4. If `host = ""' for the entry found in the `db' table, AND PRIV
     with the privileges for the host in the `host' table, i.e.  remove
     all privileges that are not "Y" in both. (If `host <> ""', PRIV is
     not affected. In such cases, `host' must have matched the
     connecting host's name at least partially. Therefore it can be
     assumed that the privileges found in this row match the connecting
     host's profile.)

  5. OR (add) PRIV with the privileges for the user from the `user'
     table, i.e. add all privileges that are "Y" in `user'.

   *Remember that if you change the tables you must do a `mysqladmin
reload' to make the changes take effect.*

   The connecting user gets the set of privileges PRIV.

   Let's show an example of the sorting and matching! Suppose that the
user table contains this:
     +-----------+----------+-
     | Host      | User     | ...
     +-----------+----------+-
     | %         | root     | ...
     | %         | jeffrey  | ...
     | localhost | root     | ...
     | localhost |          | ...
     +-----------+----------+-

   Then the search order will be:

   * localhost/root

   * localhost/any

   * any/jeffrey

   * any/root

   So jeffrey attempting to connect on localhost will be matched by the
`localhost/any' line, not by the `any/jeffrey' line. The first match
found is used!

   So if you have access problems, print out the user table, sort it by
hand, and see where the match is being made.

   Here follows an example to add a user 'custom' that can connect from
hosts 'localhost', 'server.domain' and 'whitehouse.gov'. He wants to
have password 'stupid'. The database 'bankaccount' he only want to use
from 'localhost' and the 'customer' database he wants to be able to
reach from all three hosts.

     shell> mysql mysql.
     mysql> insert into user (host,user,password)
            values('localhost','custom',password('stupid'));
     mysql> insert into user (host,user,password)
            values('server.domain','custom',password('stupid'));
     mysql> insert into user (host,user,password)
            values('whitehouse.gov','custom',password('stupid'));
     
     mysql> insert into db
            (host,db,user,Select_priv,Insert_priv,Update_priv,Delete_priv,
             Create_priv,Drop_priv)
            values
            ('localhost','bankaccount','custom','Y','Y','Y','Y','Y','Y');
     mysql> insert into db
            (host,db,user,Select_priv,Insert_priv,Update_priv,Delete_priv,
             Create_priv,Drop_priv)
            values
            ('%','customers','custom','Y','Y','Y','Y','Y','Y');

   You can of course also use xmysqladmin, mysql_webadmin, mysqladmin
and even xmysql to insert/change and update values in the privilege
tables.  You can find these utilities in the Contrib directory.

The privilege tables
====================

   The grant tables privileges on rows are *select*, *insert*, *update*
and *delete*.

   The table and database privileges are *create* and *drop*.  Create
and drop are for both tables and databases. Since a user with a drop
grant can delete any table, this is the same thing as a drop grant for
the database.

   Other privileges give the right to use files (for `LOAD DATA INFILE'
and `SELECT INTO OUTFILE') and to use the administrative commands
*shutdown*, *reload*, *refresh* and *process*.

   The privilege system is based on 3 tables.

`user' table
     Contains all host+user combinations that are allowed to connect to
     the mysql server, together with their optional passwords. The
     `user' table has the following columns:      Field                Type                 Key           Default       
     Host                 char(60)             PRI           ""            
     User                 char(16)             PRI           ""            
     Password             char(16)             -             ""            
     Select_priv          enum('N','Y')        -             N             
     Insert_priv          enum('N','Y')        -             N             
     Update_priv          enum('N','Y')        -             N             
     Delete_priv          enum('N','Y')        -             N             
     Create_priv          enum('N','Y')        -             N             
     Drop_priv            enum('N','Y')        -             N             
     Reload_priv          enum('N','Y')        -             N             
     Shutdown_priv        enum('N','Y')        -             N             
     Process_priv         enum('N','Y')        -             N             
     File_priv            enum('N','Y')        -             N             



`db' table
     Contains which databases a host+user is allowed to use, and what
     he can do with the tables in each database. The `db' table has the
     following columns:      Field                       Type          Key           Default       
     Host                        char(60)      PRI           ""            
     Db                          char(64)      PRI           ""            
     User                        char(16)      PRI           ""            
     Select_priv                 enum('N','Y') -             N             
     Insert_priv                 enum('N','Y') -             N             
     Update_priv                 enum('N','Y') -             N             
     Delete_priv                 enum('N','Y') -             N             
     Create_priv                 enum('N','Y') -             N             
     Drop_priv                   enum('N','Y') -             N             



`host' table
     Is only used in big networks as a lookup for empty host entries in
     the db table.  This means that if you want a user to be able to
     use the database from all hosts in your network, you should put "
     as the host name in the db table.  In this case the `host' table
     should contain a entry for every host in your network. The `host'
     table has the following columns:      Field                       Type          Key           Default       
     Host                        char(60)      PRI           ""            
     Db                          char(64)      PRI           ""            
     Select_priv                 enum('N','Y') -             N             
     Insert_priv                 enum('N','Y') -             N             
     Update_priv                 enum('N','Y') -             N             
     Delete_priv                 enum('N','Y') -             N             
     Create_priv                 enum('N','Y') -             N             
     Drop_priv                   enum('N','Y') -             N             



   * The HOST and DB columns may contain a string with the SQL
     wildcards `%' and `_'. Leaving any of these columns empty is
     equivalent to setting it to '%'.

   * A HOST may be `localhost', a hostname, an IP number or a string
     with wildcards. An empty host in the db table means any host in
     the host table.  An empty host in the host or user table means *any
     host that can create a TCP connection to your server*.

   * A DB is the name of a database or an SQL regexp.

   * An empty USER column means any username will do. One can't have
     wildcards in the user name.

   * A user not matching anything in the `user' table will be processed
     as a no-name user.

   * The privileges from the user table are OR'ed to the `db' table.
     This means that a superuser only needs to be in the user table
     with all privilege-flags set to `Y'.

   You can use an entry like `123.444.444.%' in the host table to give
every user on an IP C-net access. To avoid the possibility that
somebody tries to fool this setup by naming a host
`123.444.444.somewhere.com', *MySQL* disallows all hostnames that start
with digits and a dot. So if your host is named something like
`1.2.foo.com' it will never be allowed with name matching. Use the IP
number in this case.

Adding new user privileges to *MySQL*
=====================================

   To add privileges to the *MySQL* database:

   This assumes the current user has insert privileges for the mysql db
table and reload privileges. The server (mysqld) has to be running. If
it is not, start it with `safe_mysqld --log &'.

     > mysql mysql
       insert into user values ('%','monty',password('something'),'Y','Y','Y','Y','Y','Y','Y','Y','Y','Y') ;
       insert into user (host,user,password) values('localhost','dummy','') ;
       insert into user values ('%','admin','','N','N','N','N','N','N','Y','N','Y','Y') ;
       quit
     > mysqladmin reload

   This makes three new users:
`Monty'
     Full superuser, but must use password when using *MySQL*.

`admin'
     Doesn't need a password but is only allowed to use `mysqladmin
     reload', `mysqladmin refresh' and `mysqladmin processlist'. May be
     granted individual database privileges through table `db'.

`dummy'
     Must be granted individual database privileges through table `db'.

Default privileges
==================

   The default privileges (set in `scripts/mysql_install_db') let root
do anything. Any user can do anything with any database whose name is
'test' or starts with 'test_'. A normal user can't use `mysqladmin
shutdown' or `mysqladmin processlist'. See the script
(`scripts/mysql_install_db') for an example on how to add other users.

   The privilege tables are read into mysqld with `mysqladmin reload'.

An example of permission setup
==============================

   A common mistake is to forget that passwords are stored encrypted,
which leads to something like:

   `INSERT INTO user VALUES
('%','jeffrey','bLa81m0','Y','Y','Y','N','N','N','N','N', 'N','N');'

   Then (of course) a `mysqladmin reload' to make the authentication
change take effect, then trying to connect to the server:

     $ ./mysql -h sqlserver -u jeffrey -p bLa81m0 test
     Access denied

   Try this instead:

     INSERT INTO user VALUES
     ('%','jeffrey',password('bLa81m0'),'Y','Y','Y','N','N','N','N','N','N','N');

   As before, `mysqladmin reload' to make the authentication change
take effect.

   Now things should work.

Why do I get this `Access denied?' error?
=========================================

   * Have you installed the *MySQL* grant tables with the script
     `mysql_install_db'? Test by executing `mysql -u root test'. This
     should not give an error. You can also check if you have a file
     'user.ISD' in the mysql database directory (ordinary
     install_dir/var/mysql/user.ISD).

   * One a fresh installation you should use 'mysql -u root mysql' to
     access the grant tables.

   * Remember that you have to do `mysqladmin reload' each time you
     change the grant tables. Otherwise the old tables are still used!

   * For testing, you should start the mysqld daemon with the
     `--without-grant-tables' option. Now you can change the *MySQL*
     grant tables and use the script `mysqlaccess' to check if your
     grant worked. `mysqladmin reload' tells the mysqld daemon to start
     using the new grant tables.

   * Even if you have access problems with perl, python, or ODBC,
     always test your privilege problems with `mysql -u user database'
     or `mysql -u user -ppassword database'. Please notice that there
     is no space between -p and the password.  One can also use the
     `--password=your_password' syntax to give the password!

   * If you get the error 'Access denied' when trying to connect to the
     database with `mysql -u user database' then you have a problem with
     the 'user' table. Check this by doing `mysql -u root mysql' and
     `select * from user'. You should get an entry with 'hostname' and
     'user' matching your computers hostname and your username. If the
     client and the server are running on the same host and you haven't
     used the `--host' option to mysql and you are not using
     MIT-pthreads, 'localhost' is a synonym for your hostname.

   * The `Access denied' error message will tell you who you are trying
     to log in as, from which host you are trying to log in, and if you
     were using a password or not. You should normally have one entry
     in the `user' table that exactly matches your host and user,
     exactly as given in the error message.

   * If you get the error 'Host ... is not allowed to connect to this
     *MySQL* server' when you try to connect to a *MySQL* server on
     another machine then you don't have any row in the user table that
     can match the remote machine!  You can fix this by using the
     command line tool 'mysql' and add a row in the user table for the
     machine/user combination from which you want to connect.  If you
     are not running *MySQL* 3.22 and don't know exactly as which
     ip/hostname you are connection, you should put an entry with '%'
     as host in the user table and restart mysqld with -log.  After
     trying to connect you can find information in the *MySQL* log how
     you really did connect.

   * If `mysql -u root test' works but `mysql -h your_hostname -u root
     test' gives 'Access denied' then you don't have the right name for
     your host in the user table. For example if you have an entry with
     host 'tcx' in the 'user' table, but your DNS tells *MySQL* that
     your hostname is 'tcx.subnet.se' then the entry will not work.
     Test by adding a record with the IP of your host in the 'user'
     table. You can, natuarally, also add a host with a wildcard (for
     example 'tcx%') in the 'user table' (but using hostnames ending
     with % is pretty insecure).

   * If you can't figure out why you get 'Access denied', remove all
     entries with wildcards (entries that contains % or _) in the
     hostname from the user table!  A very common error is that one
     inserts a new user with host='%' and user='some user' and thinks
     that this will allow one to connect also from the same machine
     `'localhost''. The reason that this doesn't work is that one has a
     more specific entry host='localhost' and user=" that is preferred
     over the new entry when connecting from localhost'!  The correct
     procedure is to insert a second entry host='localhost' and
     user='some_user' or remove the entry with user=".

   * When using MIT-pthreads, localhost is never used. All connections
     to the mysqld daemon is via TCP IP and you must have your real
     hostname in 'user' even if you are running the client on the same
     host as the server.

   * If you get the error 'Access to database denied' then you have a
     problem with the db table. If the used entry in the db table has
     an empty hostname, check also the corresponding entry in the
     'host' table.

   * If `mysql -u user database' works on the server machine, but
     `mysql -u host -u user database' doesn't work on another client
     machine, then you don't have the client machine in the 'user' or
     the 'db' table.

   * If you can't get password to work, remember that passwords must be
     inserted with the PASSWORD function. *Note Privilege example::

   * If `mysql -u user test' works but `mysql -u user other_database'
     doesn't work, you don't have the other_database in the 'db' table.

   * If you get 'Access to database denied' when using the `SELECT ...
     INTO OUTFILE' or `LOAD DATA' SQL commands then you probably don't
     have the `File_priv' privilege set for you in the user table.

   * If everything else fails, start the `mysqld' daemon with:
     `--debug=d,general,query'. This will print info about the host and
     user that tries to connect and also information about each command
     issued. *Note Debugging::.

   * If you have any other problems with the *MySQL* grant tables and
     feel you must post the problem to the list, always add a dump of
     the *MySQL* grant tables. You can dump the tables with the
     `mysqldump mysql' command. As always, post your problem with the
     `mysqlbug' script.

   * If you get the error `Can't connect to local mySQL server' or
     `Can't connect to *MySQL* server on some_hostname' this means that
     the daemon mysqld is not running or you are trying to connect to
     the wrong socket or port.  Check that the socket exists (normally
     /tmp/mysql.sock) or try to connect to the port with telnet:
     `telnet hostname 3306'.  You can also try `mysqladmin version' to
     get some more information.

   * If you get `Access denied' when you run a client without any
     options, check that you don't have any old password in any of your
     options files!  *Note option_files::

How to make *MySQL* secure against crackers
===========================================

   To make a *MySQL* system secure you should think about the following:

   bullet Use passwords for all *MySQL* users. Remember that anyone can
     log in as any other person as simply as 'mysql -user other_user
     database'.  This is common behaviour with all client/server
     applications.  You can change the password of all users by editing
     the `mysql_install_db' script or only for the *MySQL* root user
     with:

          mysql -u root -e "update user set password=password('new_password')
          where user='root'" mysql

   bullet Don't start the *MySQL* deamon as root. mysqld can be run as
     any user.  You can also add a new user 'mysql' to make everything
     even more crash-proof.  You don't need to change the root user
     name in the 'user' table even if you run mysqld as another user,
     as *MySQL* user has nothing to do with Unix users. To start mysqld
     as another user, you can edit the mysql.server script to start
     mysqld as another user.  Normally this is done with the 'su'
     command.

   bullet Check that only the mysqld user has read/write privileges to
     the database directories.

   bullet Don't give 'Process_priv' privileges to all users. Anyone can
     check if one changes a password with the 'mysqladmin processlist'
     command.  mysqld saves an extra connection for a user with
     'Process_priv' privileges so that a root user can log in and check
     things even if all normal connections are in use.

   bullet Don't give 'File_priv' to all users.  If a user has this
     privilege he can write a file anywhere in the file system with the
     privileges of the mysqld daemon!  To make this a bit safer, all
     files generated with `SELECT INTO OUTFILE' are generated readable
     by all and one can't overwrite existing files.

   bullet If you don't trust your DNS, you should use IP's instead of
     hostnames in the privilege tables.  The -secure option to mysqld
     should in principle make hostnames safe.  In any case one should
     be real careful about using wildcards with hostnames!

   bullet If you put a root password in the mysql.server script, you
     should make this only readable for root.

   The following options to `mysqld' affects security:

`--secure'
     Check that the ip that was returned from `get_hostbyname' resolves
     back to the original hostname. This is done to make it harder for
     someone on the outside to get access by simulating another host.
     This options also adds some sanity checks of hostnames.  This is
     turned off by default in *MySQL* 3.21 since it sometimes takes a
     long time to check this.  *MySQL* 3.22 caches hostnames and has
     this enabled as default.

`--skip-grant-tables'
     Do not use the privilege system att all. This gives everyone *full
     access* to all databases!

`--skip-name-resolve'
     Hostnames are not resolved.  All hostnames in the privilege tables
     must be IP-numbers or 'localhost'.

`--skip-networking'
     Don't allow connections over the network (TCP/IP).  All
     connections to mysqld are done with Unix sockets. This options
     doesn't work very good on systems that uses MIT-pthreads as
     MIT-pthreads doesn't support Unix sockets.

*MySQL* language reference
**************************

Literals. How do you write strings and numbers?
===============================================

Strings
-------

   A string may have ' or " around it.

   \ is a escape character. The following escape characters are
recognised:
`\0'
     An ascii 0 character.

`\n'
     A newline character.

`\t'
     A tab character.

`\r'
     A return character.

`\b'
     A backspace character.

`\''
     A `'' character.

`\"'
     A `"' character.

`\\'
     A `\' character.

`\%'
     A `%' character. This is used in wildcard strings to search for
     `%'.

`\_'
     A `_' character. This is used in wildcard strings to search for
     `_'.

     A ' inside a string started with ' may be written as ''.
     A " inside a string started with " may be written as "".

   Some example selects that shows how it works.
     MySQL> select 'hello', "'hello'", '""hello""', '''h''e''l''l''o''', "hel""lo";
     1 rows in set (0.00 sec)
     
     +-------+---------+-----------+-------------+--------+
     | hello | 'hello' | ""hello"" | 'h'e'l'l'o' | hel"lo |
     +-------+---------+-----------+-------------+--------+
     | hello | 'hello' | ""hello"" | 'h'e'l'l'o' | hel"lo |
     +-------+---------+-----------+-------------+--------+

     mysql> select 'hello', "hello", '""hello""', "'ello", 'e''l''lo', '\'hello';
     1 rows in set (0.00 sec)
     
     +-------+-------+-----------+-------+--------+--------+
     | hello | hello | ""hello"" | 'ello | e'l'lo | 'hello |
     +-------+-------+-----------+-------+--------+--------+
     | hello | hello | ""hello"" | 'ello | e'l'lo | 'hello |
     +-------+-------+-----------+-------+--------+--------+

     mysql> select "This\nIs\nFour\nlines";
     1 rows in set (0.00 sec)
     
     +--------------------+
     | This
     Is
     Four
     lines |
     +--------------------+
     | This
     Is
     Four
     lines |
     +--------------------+

   If you want to insert binary data into a blob the following
characters must be represented by escape sequences:
`\0'
     Ascii 0. Should be replaced with "\0" (A backslash and a 0 digit).

`\'
     Ascii 92, backslash

`''
     Ascii 39, Single quote

`"'
     Ascii 33, Double quote

   One doesn't have to escape `"' inside `'' and `"' inside `''.

   If you write C code you can use the C API function
`mysql_escape_string(char *to,char *from,uint length)' to escape
characters for the `INSERT' clause. (Note that 'to' must be at least 2
times bigger than from). In perl you can use the `quote' function.

   You should run the escape function on every possible string that may
have a one of the above special characters!

Numbers
-------

   Integers are just a sequence of digits. Floats use `.' as a decimal
separator.

   Examples of valid numbers are: `1221', `294.42', `-32032.6809e+10'.

`NULL'
------

   When using the text file export formats, `NULL' may be represented
by `\N'. *Note Load::

Database, table, index and column names
---------------------------------------

   Database, table, index and column names all follow the same rules in
*MySQL*.

   A name consist of alphanumeric characters from the default character
set and also '_' and '$'. The default character set is ISO-8859-1
Latin1, but may be changed when compiling *MySQL*.

   Since *MySQL* needs to be able to decide if something is a name or a
number the following special cases occurs.

   * A database-, table- or column name can have up to 64 characters. An
     `alias' can have up to 128 characters.

   * A name can not consist of only numbers.

   * A name may start with a number. This is a difference from many
     other systems!

   * It is not recommended to use names like `1e'. This is because
     expressions like `1e+1' may be interpreted like the expression `1e
     + 1' or the number `1e+1'.

   Punctuation characters like `.' and `@' are not allowed in names
since they will be used to extend *MySQL*.

   In *MySQL* you can refer to a column with some of the following
syntaxes:

   * column

   * table.column

   * database.table.column  (New in MySQL 3.22)

   If you are using 'column' or 'table.column' you will get an error if
the name is not unique among the used tables!

Column types
============

   The following column types are supported:

   * M means Max display size.

   * L means the actual length in a single row.

   * M means the maximum length.

   * D means the number of decimals.

Name                          Description                            Size  
TINYINT[(M)] [UNSIGNED]        A very small integer. Signed range    1     
[ZEROFILL]                    -128 - 127. Unsigned range 0 - 255.          
SMALLINT[(M)]. [UNSIGNED]      A small integer. Signed range -32768  2     
[ZEROFILL]                    - 32767. Unsigned range 0 - 65535.           
MEDIUMINT[(M)] [UNSIGNED]      A medium integer. Signed range        3     
[ZEROFILL]                    -8388608-8388607. Unsigned range 0 -         
                              16777215.                                    
INT[(M)] [UNSIGNED]            A normal integer. Signed range        4     
[ZEROFILL]                    -2147483648 - 2147483647. Unsigned           
                              range 0 - 4294967295.                        
BIGINT[(M)] [UNSIGNED]         A large integer. Signed range         8     
[ZEROFILL]                    -9223372036854775808 -                       
                              9223372036854775807. Unsigned Range 0        
                              - 18446744073709551615.  Because all         
                              arithmetic is done with signed BIGINT        
                              or DOUBLE, one shouldn't use unsigned        
                              big integers bigger than                     
                              9223372036854775807 (63 bits) with           
                              anything else than bit functions!            
FLOAT(Precision)               A small floating point number.        4     
                              Precision can be 4 or 8. FLOAT(4) is a       
                              single precision number and FLOAT(8)         
                              is a double precision number (se the         
                              DOUBLE entry). This syntax is for            
                              ODBC compatibility. Range                    
                              -3.402823466E+38F - -1.175494351E-38,        
                              0, -1.175494351E-38 -                        
                              3.402823466E+38F.                            
FLOAT[(M,D)]                   A small floating point number.        4     
                              Cannot be unsigned. Range                    
                              -3.402823466E+38F - -1.175494351E-38,        
                              0, -1.175494351E-38 -                        
                              3.402823466E+38F.                            
DOUBLE PRECISION[(M,D)]        A normal floating point number.       8     
                              Cannot be unsigned. Range                    
                              -1.7976931348623157E+308 -                   
                              -2.2250738585072014E-308, 0,                 
                              2.2250738585072014E-308 -                    
                              1.7976931348623157E+308.                     
REAL[(M,D)]                   Same as DOUBLE                         8     
DECIMAL [(M,D)]                An unpacked floating point number.    M+D   
                              Cannot be unsigned. Currently the            
                              same range maximum range as a double.        
                              Behaves as a CHAR column                     
NUMERIC [(M,D)]                Same as DECIMAL                       M+D   
TIMESTAMP [(M)]                An automatic timestamp. If you have   4     
                              many TIMESTAMP columns only the first        
                              one is automatic                             
DATE                           A type to store date information.     3     
                              Uses the "YYYY-MM-DD" syntax, but may        
                              be updated with a number or a string.        
                              Understands at least the following           
                              syntaxes: 'YY-MM-DD', 'YYYY-MM-DD',          
                              'YYMMDD' and full timestamps                 
                              (YYYYMMDDHHMMDD). Range 0000-00-00 to        
                              9999-12-31.                                  
TIME                           A type to store time information.     3     
                              Uses the "HH:MM:SS" syntax, but may be       
                              updated with a number or a string.           
                              Understands at least the following           
                              syntaxes: 'HH:MM:SS, 'HHMMSS',               
                              'HHMM', 'HH'.                                
DATETIME                       A type to store date and time         8     
                              information. Format "YYYY-MM-DD              
                              HH:MM:SS". Takes 8 bytes. Range              
                              '0000-01-01 00:00:00' - '9999-12-31          
                              23:59:59'.                                   
YEAR                           A type to store years. Format "YYYY"  1     
                              or "YY". Takes 1 byte. Range 0,              
                              1901-2155.  2 digits years in the            
                              range 00-69 is assumed to be                 
                              2000-2069 and will be sorted                 
                              correctly. (now type for *MySQL*             
                              3.22)                                        
CHAR(M) [binary]               A fixed length string that is always  M     
                              filled up with spaces to the                 
                              specified length. Range 1 - 255              
                              characters. All end space are removed        
                              when retrieved. Is sorted and                
                              compared case insensitively unless the       
                              binary keyword is given.                     
VARCHAR(M) [binary]            A variable length string that is      L+1   
                              stored with its length. NOTE: All end        
                              space are removed when storing it            
                              (not ANSI SQL). Maximum range 1 - 255        
                              characters.  Is sorted and compared          
                              case insensitively unless the binary         
                              keyword is given.                            
TINYTEXT and TINYBLOB          A `TEXT'/`BLOB' with max length of    L+1   
                              255 characters.                              
TEXT and BLOB                  A `TEXT'/`BLOB' with max length of    L+2   
                              65535 characters.                            
MEDIUMTEXT and MEDIUMBLOB      A `TEXT'/`BLOB' with max length of     L+3  
                              16777216 characters.                         
LONGTEXT and LONGBLOB          A `TEXT'/`BLOB' with max length of     L+4  
                              4294967295 characters.                       
ENUM('value','value2',...)     A string object that can have only    1 or  
                              one set of allowed values (or NULL).   2     
                              *Note Type details::                         
SET('value','value2',...)      A string object that can have one or  1-8   
                              many values of a set of allowed              
                              values. *Note Type details::.                

More about data types
---------------------

Database size info.
...................

   In the above table L means the actual length of a instance and M the
maximum length. So L+1 for "abcd" means 5 bytes in the database.

   If you use any data type with an L in the length field you will get a
variable length record format.

The numeric types
.................

   All integer types can have an optional argument `unsigned'.  This
can be used when you only want to allow positive numbers in the column
or you need a little bigger numerical range for the column.

   Also for all integer columnsn, the optional argument `ZEROFILL' means
that the column will be padded with zeroes up to the maximum length.

   Max display size and decimals are for formatting and calculation of
maximum column width.

   When storing a value in an integer that is outside its range,
*MySQL* stores the maximum (or minimum) possible value. When doing an
`ALTER TABLE' or `LOAD DATA INFILE' one gets these conversions as
'warnings'.  We have on the TODO to fix INSERT and UPDATE so they can
return warnings, but this is scheduled for the next protocol change.

   For example when storing `-999999999999999' into an int column the
value ends up as `-2147483648'. And `9999999999999999' ends up as
`2147483647'.

   And if the `int' is unsigned the stored values above becomes `0' and
`4294967296'.

   The same rules go for all other integer types.

   When returning data for an int(4) column that exceeds the allocated
space, *MySQL* will return 9.99. If the operation is an `UPDATE' a
warning will be issued.

   Note that a type like `decimal(4,2)' means maximum 4 characters with
two decimal points. That gives a range between `-.99' -> `9.99'.

   To avoid some rounding problems, *MySQL* always rounds everything
that it stores in any floating point column according to the number of
decimals. This means that `2.333' stored into `float(8,2)' is stored as
`2.33'.

`TIMESTAMP' type
................

   Has a range of 1 Dec 1970 time 0.00 to sometime in the year 2106 and
a resolution of one second. A TIMESTAMP column will automatically be
updated on `INSERT' and `UPDATE' statements if set to `NULL' or if the
column is not updated in the statement. Can be (part of) an index.
Note that if you have many timestamp columns in a row, then only the
first timestamp column will be automatically updated. Any timestamp
column will be set to the current time if set to `NULL'. Depending on
the display size one gets one of the following formats: "YYYY-MM-DD
HH:MM:SS", "YY-MM-DD HH:MM:SS", "YYYY-MM-DD" or "YY-MM-DD".

`TEXT' and `BLOB' types
.......................

   These are objects that can have a variable length without upper
limit.  All TEXT and BLOB objects are stored with their length (saved
in 1 to 4 bytes depending on the type of object). The maximum `TEXT' and
`BLOB' length you can use is dependent on available memory and client
buffers. The only differences between `TEXT' and `BLOB' is that `TEXT'
is sorted and compared case insensitively while `BLOB' is compared case
sensitively (by character values). `TEXT' and `BLOB' objects CANNOT be
an index.

   A BLOB is a binary large object which can hold any amount of data.
There are 4 kinds of blobs *Note Column types::. Normally one can regard
a BLOB as a VARCHAR without a specified limit.

   `TEXT' is a `BLOB' that is sorted and compared case insensitively.

   A `BLOB'/`TEXT' column may not be bigger that the message buffer.
Note that you have to change the message buffer on both the server and
the client. *Note MySQL parameters::.

   `MyODBC' defines `BLOB's as `LONGVARBINARY' and `TEXT's as
`LONGVARCHAR'.

   Restrictions for `BLOB' and `TEXT' columns:

  1. A `BLOB' or `TEXT' cannot be an index or a part of an index

  2. When one sorts or groups a `BLOB' or `TEXT', only the first
     `max_sort_length' (default 1024) of the blob is used. This value
     can be changed by the `-O' option when starting the mysqld daemon.
     One can group on an expression involving a `BLOB'/ `TEXT': `SELECT
     id,SUBSTR(blob,1,100) GROUP BY 2'

  3. There is no end space truncation for `BLOB' and `TEXT' as there is
     for `CHAR' and `VARCHAR'.

`ENUM' type
...........

   A string object that can have only one of a set of allowed values.
The value to be stored may be given case independently. If one tries to
store a non-existing value, "" is stored. If used in a number context
this object returns/stores the value index. If there is less than 255
possible values this object occupies 1 byte, else two bytes (with a
maximum of 65535 different values). Note that if an integer is put in
the `ENUM' you get the corresponding string with the first counting as
number 1. (0 is reserved for wrong enum values). Sorting on `ENUM'
types are done according to the order of the strings in the enum.  If
declared `NOT NULL' the default value is the first value, else the
default value is `NULL'.

   For example the column `test ENUM("one","two", "three")' can have
any of these values:

     NULL
     "one"
     "two"
     "three"

`SET' type
..........

   A string object that can have one or many values from a set of
allowed values. Each value is separated by a ','. If used in a number
context this object returns/stores the bit positions of the used
values. This object occupies (number_of_different_values-1)/8+1 bytes,
rounded up to 1,2,3,4 or 8. One can't have more than 64 different
values. Note that if an integer is put in the `SET' you get the
corresponding string with the first bit corresponding to the first
string. Sorting on `SET' types are done numerically.

   For example the column `test SET("one","two") NOT NULL' can have any
of these values:

     ""
     "one"
     "two"
     "one,two"

   Normally on SELECT on a SET column with LIKE or FIND_IN_SET():

     SELECT * from banner where banner_group LIKE '%value%';
     SELECT * from banner where FIND_IN_SET('value',banner_group)>0;

   But the following will also work:

     SELECT * from banner where banner_group = 'v1,v2';  ;Exact match
     SELECT * from banner where banner_group & 1;        ;Is in first group

Choosing the right type for a column
------------------------------------

   Try to use the most precise type in all cases. For example for an
integer between 1-99999 a `unsigned mediumint' is the best type.

   A common problem is representing monetary values accurately. In
*MySQL* you should use the `DECIMAL' type. This is stored as a string
so no loss of accuracy should occur. If accuracy is not to too
important the `DOUBLE' type may also be good enough.

   For high precision you can always convert to a fixed point type
stored in a `BITINT'. This allows you to do all calculations with
integers and only convert the result back to floating point.

   *Note Row format::.

Column indexes
--------------

   You can have indexes on all *MySQL* columns except `BLOB' and `TEXT'
types. Using indexes on the relevant columns is the best way to improve
the performance of selects.

   For `CHAR' and `VARCHAR' columns you can have an index on a prefix.
The example below shows how to create an index for the first 10
characters of a column. This is much faster and requires less disk space
than having an index on the whole column.

     CREATE TABLE test (
     name CHAR(200) NOT NULL,
     KEY index_name (name(10));

Multiple column indexes
-----------------------

   *MySQL* can have one index on parts of different columns.

   A multiple-column index can be considered a sorted array where the
columns are concatenated.  This makes for fast queries where the first
column in the index is a known quantity and the other columns are not.

   Suppose that you have a table:

     CREATE TABLE test (
     id INT NOT NULL,
     last_name CHAR(30) NOT NULL,
     first_name CHAR(30) NOT NULL,
     PRIMARY KEY (id),
     INDEX name (last_name,first_name));

   Then the index `name' is an index over last_name and first_name.

   The `name' index will be used in the following queries:

     SELECT * FROM test WHERE last_name="Widenius";
     
     SELECT * FROM test WHERE last_name="Widenius" AND first_name="Michael";
     
     SELECT * FROM test WHERE last_name="Widenius" AND
                              (first_name="Michael" OR first_name="Monty");
     
     SELECT * FROM test WHERE last_name="Widenius" and
                              first_name >="M" and first_name < "N";

   The `name' index will NOT be used in the following queries:

     SELECT * FROM test WHERE first_name="Michael";
     
     SELECT * FROM test WHERE last_name="Widenius" or first_name="Michael";

Type mapping to ease moving table definitions between different databases engines
---------------------------------------------------------------------------------

   To support easier use of code from different SQL vendors, *MySQL*
does supports the following mappings:

binary(num)                          char(num) binary                     
char varying                         varchar                              
float4                               float                                
float8                               double                               
int1                                 tinyint                              
int2                                 smallint                             
int3                                 mediumint                            
int4                                 int                                  
int8                                 bigint                               
long varbinary                       blob                                 
long varchar                         text                                 
middleint                            mediumint                            
varbinary(num)                       varchar(num) binary                  

Functions for use in `SELECT' and `WHERE' clauses
=================================================

   A `select_expression' or `where_definition' can consist of any
expression using the following functions:

   In the examples below the output of the `mysql' program has been
shortened.  So this:

     mysql> select mod(29,9);
     1 rows in set (0.00 sec)
     
     +-----------+
     | mod(29,9) |
     +-----------+
     |         2 |
     +-----------+

   Has been converted to:

     mysql> select mod(29,9);                ->      2

Grouping functions
------------------

`('
`)'
     Parenthesis. Force order of evaluation in a expression.
          mysql> select 1+2*3;                     ->      7
          mysql> select (1+2)*3;                   ->      9

Normal arithmetic operations
----------------------------

`+'
     Addition

`-'
     Subtraction.

`*'
     Multiplication

`/'
     Division. A division by zero results in a `NULL'.
          mysql> select 102/(1-1);                 ->      NULL

Bit functions
-------------

   These have a range of maximum 64 bits because *MySQL* uses bigint
(64 bit) arithmetic.
`|'
     Bitwise OR.
          mysql> select 29 | 15;                   ->     31

`&'
     Bitwise and.
          mysql> select 29 & 15;                   ->      13

`<<'
     Shift a longlong number to the right
          mysql > select 1 << 2			->	4

`<<'
     Shift a longlong number to the left
          mysql > select 4 >> 2			->	1

`BIT_COUNT()'
     Number of set bits in an argument.
          mysql> select bit_count(29);             ->      4

Logical operations
------------------

   All logical function return 1 (TRUE) or 0 (FALSE).
`NOT'
`!'
     Logical NOT. Return 1 if argument is 0 else return 0.
          mysql> select NOT 1;                    ->      0
          mysql> select NOT NULL;                 ->      NULL
          mysql> select ! (1+1);                  ->      0
          mysql> select ! 1+1;                    ->      1

`OR'
`||'
     Logical OR. Return 1 if any of the arguments are non 0 and not
     NULL.
          mysql> select 1 || 0;                   ->      1
          mysql> select 0 || 0;                   ->      0
          mysql> select 1 || NULL;                ->      1

`AND'
`&&'
     Logical AND. Return 1 if all of the arguments are non 0 or NULL
          mysql> select 1 && NULL;                ->      0
          mysql> select 1 && 0;                   ->      0

Comparison operators
--------------------

   Returns 1 (TRUE), 0 (FALSE) or `NULL'. These functions work for both
numbers and strings. *MySQL* uses the following rules to decide how the
compare is done:
   * If both arguments to a compare operation are strings, compare as
     strings.

   * If both arguments are integers, compare as integers.

   * If one of the arguments is a `TIMESTAMP' or `DATETIME' column and
     the other argument is a constant. In this case the constant is
     converted to a timestamp before the comparasion. This is to be
     more ODBC friendly.

   * In all other cases compare as floating point numbers (real).

   If one or both of the arguments are `NULL' the result of the
comparison is `NULL'.

`='
     Equal.
          mysql> select 1 = 0;                    ->      0
          mysql> select '0' = 0;                  ->      1
          mysql> select '0.0' = 0;                ->      1
          mysql> select '0.01' = 0;               ->      0
          mysql> select '.01' = 0.01;             ->      1

`<>'
`!='
     Not equal.
          mysql> select '.01' <> '0.01';          ->      1
          mysql> select .01 <> '0.01';            ->      0
          mysql> select 'zapp' <> 'zappp';        ->      1

`<='
     Smaller than or equal.
          mysql> select 0.1 <= 2;                 ->      1

`<'
     Smaller than.
          mysql> select 2 <= 2;                   ->      1

`>='
     Bigger than or equal.
          mysql> select 2 >= 2;                   ->      1

`>'
     Bigger than.
          mysql> select 2 > 2;                    ->      0

`ISNULL(A)'
     Returns 1 if `A' is `NULL' else 0.
          mysql> select isnull(1+1);              ->      0
          mysql> select isnull(1/0);              ->      1

`A BETWEEN B AND C'
     `A' is bigger or equal as `B' and `A' is smaller or equal to `C'.
     Does the same thing as `(A >= B AND A <= C)' if all arguments are
     of the same type.  It's the first argument (`A') that decides how
     the comparison should be done!  If `A' is a string expression,
     compare as case insensitive strings. If `A' is a binary string,
     compare as binary strings. If `A' is an integer expression compare
     as integers, else compare as reals.
          mysql> select 1 between 2 and 3;        ->      0
          mysql> select 'b' between 'a' and 'c';  ->      1
          mysql> select 2 between 2 and '3';      ->      1
          mysql> select 2 between 2 and 'x-3';    ->      0

String comparison functions
---------------------------

     Normally if one expression that is compared is not case sensitive
     than the compare is done case insensitively.

`expr IN (value,...)'
     Returns 1 if expr is any of the values in the `IN' list, else it
     returns 0.  If all values are constants, then all values are
     evaluated according to the type of expr and sorted. The search for
     the item is then done by using a binary search. This means `IN' is
     very quick when used with constants in the `IN' part.  If `expr'
     is a string expression then string compare is done case
     sensitively if `expr' is case sensitive.
          mysql> select 2 in (0,3,5,'wefwf');               ->      0
          mysql> select 'wefwf' in (0,3,5,'wefwf');         ->      1

`expr NOT IN (value,...)'
     Same as `NOT (expr IN (value,...))'

`expr LIKE expr'
     SQL simple regular expression comparison. Returns 1 (TRUE) or 0
     (FALSE).  With `LIKE' you have two wild characters.

     `%'           Matches any number of characters, even   
                   zero characters.                         
     `_'           Matches exactly one character.           
     `\%'          Matches one `%'.                         
     `\_'          Matches one `_'.                         

          mysql> select 'David!' like 'David_';             ->      1
          mysql> select 'David!' like 'David\_';            ->      0
          mysql> select 'David_' like 'David\_';            ->      1
          mysql> select 'David!' like '%D%v%';              ->      1
          mysql> select 10 like '1%';                       ->      1
     `LIKE' is allowed on numerical expressions! (Extension)

`expr NOT LIKE expr'
     Same as `NOT (expr LIKE expr)'.

`expr REGEXP text_literal'
`expr RLIKE text_literal'
     Checks string against extended regular expr. *Note Regexp::.
     `RLIKE' is for `mSQL' compatibility. NOTE: Because *MySQL* uses the
     C escape syntax in strings (`\n') You must double any `'\'' that
     you uses in your REGEXP strings.
          mysql> select 'Monty!' regexp 'm%y%%';            ->      0
          mysql> select 'Monty!' regexp '.*';               ->      1
          mysql> select 'new*\n*line' regexp 'new\\*.\\*line'

`expr NOT REGEXP expr'
     Same as `NOT (expr REGEXP expr)'.

`STRCMP()'
     Returns 0 if the strings are the same. Otherwise return -1 if the
     first argument is smaller according to the current sort-order,
     otherwise return 1.
          mysql> select strcmp('text', 'text2');            -> -1
          mysql> select strcmp('text2', 'text');            -> 1
          mysql> select strcmp('text', 'text');             -> 0

Control flow functions
----------------------

`IFNULL(A,B)'
     If `A' is not `NULL' it returns `A', else `B'.
          mysql> select ifnull(1,0);        -> 1
          mysql> select ifnull(0,10);       -> 0
          mysql> select ifnull(1/0,10);     -> 10
          mysql> select ifnull(1/0,'yes');  -> 'yes'

`IF(A,B,C)'
     If `A' is true (`A <> 0' and `A <> NULL') then return `B', else
     return `C'.  A is evaluated as an INTEGER, which means that if you
     are using floats you should also use a comparison operation.
          mysql> select if(1>2,2,3);        -> 3
          mysql> select if(1<2,'yes','no'); -> 'yes'

Mathematical functions
----------------------

   All mathematical functions returns `NULL' in the case of a error.
`-'
     Sign. Changes sign of argument.
          mysql> select - 2;                -> -2

`ABS()'
     Absolute value.
          mysql> select abs(2);             -> 2
          mysql> select abs(-32);           -> 32

`SIGN()'
     Sign of argument. Returns -1, 0 or 1.
          mysql> select sign(-32);          -> -1
          mysql> select sign(0);            -> 0
          mysql> select sign(234);          -> 1

`MOD()'
`%'
     Modulo (like % in C).
          mysql> select mod(234, 10);       -> 4
          mysql> select 253 % 7;            -> 1
          mysql> select mod(29,9);                -> 2

`FLOOR()'
     Largest integer value not greater than x.
          mysql> select floor(1.23);              -> 1
          mysql> select floor(-1.23);             -> -2

`CEILING()'
     Smallest integer value not less than x.
          mysql> select ceiling(1.23);            -> 2
          mysql> select ceiling(-1.23);           -> -1

`ROUND(N)'
     Round argument `N' to an integer.
          mysql> select round(-1.23);             -> -1
          mysql> select round(-1.58);             -> -2
          mysql> select round(1.58);              -> 2

`ROUND(Number,Decimals)'
     Round argument `Number' to a number with `Decimals' decimals.
          mysql> select ROUND(1.298, 1);          -> 1.3

`EXP(N)'
     Returns the value of `e' (the base of natural logarithms) raised to
     the power of `N'.
          mysql> select exp(2);                   -> 7.389056
          mysql> select exp(-2);                  -> 0.135335

`LOG(X)'
     Return the natural logarithm of `X'.
          mysql> select log(2);             -> 0.693147
          mysql> select log(-2);            -> NULL

`LOG10(X)'
     return the base-10 logarithm of `X'.
          mysql> select log10(2);           -> 0.301030
          mysql> select log10(100);                 -> 2.000000
          mysql> select log10(-100);                -> NULL

`POW(X,Y)'
`POWER(X,Y)'
     Return the value of `X' raised to the power of `Y'.
          mysql> select pow(2,2);           -> 4.000000
          mysql> select pow(2,-2);                  -> 0.250000

`sqrt(X)'
     Returns the non-negative square root of `X'.
          mysql> select sqrt(4);            -> 2.000000
          mysql> select sqrt(20);           -> 4.472136

`PI()'
     Return the value of PI.
          mysql> select PI();               -> 3.141593

`COS(X)'
     Return the cosine of `X', where `X' is given in radians.
          mysql> select cos(PI());                  -> -1.000000

`SIN(X)'
     Return the sine of `X', where `X' is given in radians.
          mysql> select sin(PI());                  -> 0.000000

`TAN(X)'
     Returns the tangent of `X', where `X' is given in radians.
          mysql> select tan(PI()+1);                -> 1.557408

`ACOS(X)'
     Return the arc cosine of `X'; that is the value whose cosine is
     `X'. If `X' is not in the range -1 to 1 `NULL' is returned.
          mysql> select ACOS(1);                  -> 0.000000
          mysql> select ACOS(1.0001);             -> NULL
          mysql> select ACOS(0);          -> 1.570796

`ASIN(X)'
     Return the arc sine of `X'; that is the value whose sine is `X'.
     If `X' is not in the range -1 to 1 `NULL' is returned.
          mysql> select ASIN(0.2);                -> 0.201358
          mysql> select ASIN('foo');              -> 0.000000

`ATAN(X)'
     Return the arc tangent of `X'; that is the value whose tangent is
     `X'.
          mysql> select ATAN(2);          -> 1.107149
          mysql> select ATAN(-2);         -> -1.107149

`ATAN2(X,Y)'
     Return the arc tangent of the two variables `X' and `Y'. It is
     similar to calculating the arc tangent of `Y / X', except that the
     signs of both arguments are used to determine the quadrant of the
     result.
          mysql> select ATAN(-2,2);               -> -0.785398
          mysql> select ATAN(PI(),0);             -> 1.570796

`COT(N)'
     Return the cotangens of `N'.
          mysql> select COT(12);          -> -1.57267341
          mysql> select COT(0);           -> NULL

`RAND([X])'
     Returns a random float, `0 <= x <= 1.0', using the integer
     expression `X' as the optional seed value.
          mysql> SELECT RAND();           -> 0.5925
          mysql> SELECT RAND(20);         -> 0.1811
          mysql> SELECT RAND(20);         -> 0.1811
          mysql> SELECT RAND();           -> 0.2079
          mysql> SELECT RAND();           -> 0.7888
     One can't do a ORDER BY on a column with RAND() values because
     ORDER BY would evaluate the column multiple times.

`MIN(X,Y...)'
     Min value of arguments. Must have 2 or more arguments, else these
     are `GROUP BY' functions. The arguments are compared as numbers.
     If no records are found `NULL' is returned.
          mysql> SELECT MIN(2,0);                         -> 0
          mysql> SELECT MIN(34,3,5,767);                  -> 3
          mysql> SELECT MIN(a) from table where 1=0;      -> NULL

`MAX(X,Y...)'
     Max value of arguments. Must have 2 or more arguments, else these
     are `GROUP BY' functions. The arguments are compared as numbers.
     If no records are found `NULL' is returned.
          mysql> SELECT MAX(34,3,5,767);                  -> 767
          mysql> SELECT MAX(2,0,4,5,34);                  -> 34
          mysql> SELECT MAX(a) from table where 1=0;      -> NULL

`DEGREES(N)'
     Return `N' converted from radians to degrees.
          mysql> select DEGREES(PI());                    -> 180.000000

`RADIANS(N)'
     Return `N' converted from degrees to radians.
          mysql> select RADIANS(90);                      -> 1.570796

`TRUNCATE(Number, Decimals)'
     Truncate number `Number' to `Decimals' decimals.
          mysql> select TRUNCATE(1.223,1);                -> 1.2
          mysql> select TRUNCATE(1.999,1);                -> 1.9
          mysql> select TRUNCATE(1.999,0);                -> 1

String functions
----------------

`ASCII(S)'
     Returns the ASCII code value of the leftmost character of `S'. If
     `S' is `NULL' return `NULL'.
          mysql> SELECT ascii(2);                         -> 50
          mysql> SELECT ascii('dx');                      -> 100

`CONV(NUMBER,FROM_BASE,TO_BASE)'
     Converts numbers between different number bases.  If any of the
     arguments is a `NULL' value, the return value is `NULL'. Max base
     is 36 and min is 2.  CONV works with 64 bit precision. If TO_BASE
     is a negative number, the NUMBER is regarded as a signed number.
          mysql> SELECT conv("a",16,2);                   -> 1010
          mysql> SELECT conv("6E",18,8);                  -> 172
          mysql> SELECT conv(-17,10,-18);                 -> -H
          mysql> SELECT conv(10+"10"+'10'+0xa,10,10);     -> 40

`BIN(N)'
     Returns the binary value of N where N is a longlong number.  This
     is same as conv(N,10,2).  If n is `NULL' the return value is
     `NULL'.
          mysql> SELECT bin(12);                          -> 1100

`OCT(N)'
     Returns the octal value of N where N is a longlong number.  This
     is same as conv(N,10,8).  If n is `NULL' the return value is
     `NULL'.
          mysql> SELECT oct(12);                          -> 14

`HEX(N)'
     Returns the hexadecimal value of N where N is a longlong number.
     This is same as conv(N,10,16).  If n is `NULL' the return value is
     `NULL'.
          mysql> SELECT hex(255);                         -> FF

`CHAR(X,...)'
     Returns a string that consists of the characters given by the
     ASCII code values of the arguments. `NULLs' are skipped.
          mysql> SELECT char(77,121,83,81,'76');          -> 'MySQL'

`CONCAT(X,Y...)'
     Concatenates strings. May have more than 2 arguments.
          mysql> SELECT CONCAT('My', 'S', 'QL');          -> 'MySQL'

`LENGTH(S)'
`OCTET_LENGTH(S)'
`CHAR_LENGTH(S)'
`CHARACTER_LENGTH(S)'
     Length of string.
          mysql> SELECT length('text');                   -> 4
          mysql> SELECT octet_length('text');             -> 4

`LOCATE(A,B)'
`POSITION(B IN A)'
     Returns position of `A' substring in `B'. The first position is 1.
     Returns 0 if `A' is not in `B'.
          mysql> select locate('bar', 'foobarbar');         -> 4
          mysql> select locate('xbar', 'foobar');           -> 0

`INSTR(A,B)'
     Returns position of first substring `B' in string `A'. This is the
     same as `LOCATE' with swapped parameters.
          mysql> select instr('foobarbar', 'bar');         -> 4
          mysql> select instr('xbar', 'foobar');           -> 0

`LPAD(A,B,C)'
     Left pad (at the start) the string A with C until A's length is B.
          mysql> select lpad('hi',4,'??')			 -> '??hi'

`RPAD(A,B,C)'
     Right pad (at the end) the string A with C until A's length is B.
          mysql> select rpad('hi',5,'?')			 -> 'hi???'

`LOCATE(A,B,C)'
     Returns position of first substring `A' in string `B' starting at
     `C'.
          mysql> select locate('bar', 'foobarbar',5);        -> 7

`LEFT(str,length)'
     Gets length in characters from beginning of string.
          mysql> select left('foobarbar', 5);             -> 'fooba'

`RIGHT(A,B)'
`SUBSTRING(A FROM B)'
     Gets `B' characters from end of string `A'.
          mysql> select right('foobarbar', 5);            -> 'arbar'
          mysql> select substring('foobarbar' from 5);    -> 'arbar'

`LTRIM(str)'
     Removes space characters from the beginning of string.
          mysql> select ltrim('  barbar');                -> 'barbar'

`RTRIM(str)'
     Removes space characters from the end of string.
          mysql> select rtrim('barbar   ');             -> 'barbar'

`TRIM([[ BOTH | LEADING | TRAILING] [ A ] FROM ] B)'
     Returns a character string with all `A' prefixes and/or suffixes
     removed from `B'. If `BOTH', `LEADING' and `TRAILING' isn't used
     `BOTH' are assumed. If `A' is not given, then spaces are removed.
          mysql> select trim('  bar   ');                      -> 'bar'
          mysql> select trim(leading 'x' from 'xxxbarxxx');    -> 'barxxx'
          mysql> select trim(both 'x' from 'xxxbarxxx');       -> 'bar'
          mysql> select trim(trailing 'xyz' from 'barxxyz');   -> 'barx'

`SOUNDEX(S)'
     Gets a soundex string from `S'. Two strings that sound 'about the
     same' should have identical soundex strings. A 'standard' soundex
     string is 4 characters long, but this function returns an
     arbitrary long string. One can use `SUBSTRING' on the result to
     get a 'standard' soundex string.  All non alpha characters are
     ignored in the given string. All characters outside the A-Z range
     are treated as vocals.
          mysql> select soundex('Hello');                 -> 'H400'
          mysql> select soundex('Bttre');                -> 'B360'
          mysql> select soundex('Quadratically');         -> 'Q36324'

`SUBSTRING(A, B, C)'
`SUBSTRING(A FROM B FOR C)'
`MID(A, B, C)'
     Returns substring from `A' starting at `B' with `C' chars. The
     variant with `FROM' is ANSI SQL 92 syntax.
          mysql> select substring('Quadratically',5,6);          -> ratica

`SUBSTRING(A,B)'
     Returns substring from `A' starting at `B'.
          mysql> select substring('Quadratically',5);            -> ratically

`SUBSTRING_INDEX(String, Delimiter, Count)'
     Returns the substring from `String' after `Count' `Delimiters'. If
     `Count' is positive the strings are searched from left else if
     count is negative the substrings are searched and returned from
     right.
          mysql> select substring_index('www.tcx.se', '.', 2);   -> 'www.tcx'
          mysql> select substring_index('www.tcx.se', '.', -2);  -> 'tcx.se'

`SPACE(N)'
     Return a string of `N' spaces.
          mysql> select SPACE(6);         -> '      '

`REPLACE(A, B, C)'
     Replaces all occurrences of string `B' in string `A' with string
     `C'.
          mysql> select replace('www.tcx.se', 'w', 'Ww');  -> 'WwWwWw.tcx.se'

`REPEAT(String, Count)'
     Repeats `String' `Count' times. If `Count <= 0' returns a empty
     string. If `String' or `Count' is `NULL' or `LENGTH(string)*count
     > max_allowed_size' returns `NULL'.
          mysql> select repeat('MySQL', 3);                -> 'MySQLMySQLMySQL'

`REVERSE(String)'
     Reverses all characters in string.
          mysql> select reverse('abc');  -> 'cba'

`INSERT(Org, Start, Length, New)'
     Replaces substring in `Org' starging at `Start' and `Length' long
     with `New'. First position in `Org' is numbered 1.
          mysql> select insert('Quadratic', 3, 4, 'What');   -> 'QuWhattic'

`INTERVAL(N, N1, N2, N3...)'
     It is required that `Nn' > `N3' > `N2' > `N1' is this function
     shall work. This is because a binary search is used (Very fast).
     Returns 0 if `N' < `N1', 1 if `N' < `N2' and so on. All arguments
     are treated as numbers.
          mysql> select INTERVAL(23, 1, 15, 17, 30, 44, 200);     -> 3
          mysql> select INTERVAL(10, 1, 10, 100, 1000);           -> 2
          mysql> select INTERVAL(22, 23, 30, 44, 200);            -> 0

`ELT(N, A1, A2, A3...)'
     Returns `A1' if `N' = 1, `A2' if `N' = 2 and so on. If `N' is less
     than 1 or bigger than the number of arguments `NULL' is returned.
          mysql> select elt(1, 'ej', 'Heja', 'hej', 'foo');  -> 'ej'
          mysql> select elt(4, 'ej', 'Heja', 'hej', 'foo');  -> 'foo'

`FIELD(S, S1, S2, S3...)'
     Returns index of `S' in `S1', `S2', `S3'... list. The complement
     of `ELT()'. Return 0 when S is not found.
          mysql> select FIELD('ej', 'Hej', 'ej', 'Heja', 'hej', 'foo');       -> 2
          mysql> select FIELD('fo', 'Hej', 'ej', 'Heja', 'hej', 'foo');       -> 0

`FIND_IN_SET(string,string of strings)'
     Returns a value 1 to N if the 'string' is in 'string of strings'.
     A 'string of strings' is a string where each different value is
     separated with a ','. If the first argument is a constant string
     and the second is a column of type SET, the FIND_IN_SET is
     optimized to use bit arithmetic!
          mysql> SELECT FIND_IN_SET('b','a,b,c,d')		-> 2
     This function will not work properly if the first argument
     contains a ','.

`LCASE(A)'
`LOWER(A)'
     Changes `A' to lower case according to current character set
     ,dmappings (Default Latin1).
          mysql> select lcase('QUADRATICALLY');           -> 'quadratically'

`UCASE(A)'
`UPPER(A)'
     Changes `A' to upper case.
          mysql> select ucase('Hej');             -> 'HEJ'

Date and time functions
-----------------------

   Some examples using more than one date function:

   Select all record with a date_field from the last 30 days.
     SELECT something FROM table WHERE TO_DAYS(NOW()) - TO_DAYS(date_field) <= 30;

   A `Date' expression may be a date string, a datetime string, a
timestamp([6 | 8 | 14]) or a number of format `YYMMDD' or `YYYYMMDD'.

   In a date expression a year may be 2 or 4 digits. 2 digits is
assumed to be in the range 1970-2069.  Dates 100-199 is converted to
2000-2999 to make year arithmetic easier! The special date '0000-00-00'
can be stored and retrieved as 0000-00-00.

   If you use a date function with a number, then if the length of the
number is 4, 8 or >= 14 then the year is assumed to have 4 digits. In
all other cases the year is assumed to be the 2 first digits in the
given number.  To be on the safe side when using dates as numbers (not
strings) one should always use 4 digit dates!  If not you will get in
trouble with year 2000 when a number 002001 is sent to the date
functions as '2001' instead of the date '20002001'.  '002001' will of
course work correctly!

   A `Time' expression may be a date string, a datetime string, a
timestamp([6 | 8 | 14]) or a number of format `HHMMSS' or
`YYYYMMDDHHMMSS'.
`DAYOFWEEK(date expr)'
     Gets weekday for `Date' (1 = Sunday, 2 = Monday, 2 = Tuesday ..)
     This is according to the ODBC standard.
          mysql> select dayofweek('1998-02-03');		-> 3

`WEEKDAY(date expr)'
     Gets weekday for `Date' (0 = Monday, 1 = Tuesday ..)
          mysql> select WEEKDAY('1997-10-04 22:23:00');	-> 5
          mysql> select WEEKDAY('1997-11-05');            -> 2

`DAYOFMONTH(date expr)'
     Returns day of month (1-31)
          mysql> select DAYOFMONTH('1998-02-03');		-> 3

`DAYOFYEAR(date expr)'
     Returns day of year (1-366)
          mysql> select DAYOFYEAR('1998-02-03');		-> 34

`MONTH(date expr)'
     Returns month (1-12)
          mysql> select MONTH('1998-02-03');		-> 02

`DAYNAME(date expr)'
     Returns the name of the day.
          mysql> select dayname("1998-02-05");            -> Thursday

`MONTHNAME(date expr)'
     Returns the name of the month.
          mysql> select monthname("1998-02-05");          -> February

`QUARTER(date expr)'
     Returns quarter (1-4).
          mysql> select QUARTER('98-04-01');		-> 2

`WEEK(date expr)'
     Returns week (1-53) on locations where Sunday is the first day of
     the year
          mysql> select WEEK('98-02-20');			-> 7

`YEAR(date expr)'
     Returns year (1000-9999).
          mysql> select YEAR('98-02-03');			-> 1998

`HOUR(time expr)'
     Returns hour (0-23)
          mysql> select HOUR('10:05:03');			-> 10

`MINUTE(time expr)'
     Returns minute (0-59).
          mysql> select MINUTE('98-02-03 10:05:03');	-> 5

`SECOND(time expr)'
     Returns seconds (1000-9999).
          mysql> select SECOND('10:05:03');		-> 3

`PERIOD_ADD(P, N)'
     Adds `N' months to period `P' (of type `YYMM' or `YYYYMM').
     Returns `YYYYMM'.
          mysql> select PERIOD_ADD(9801,2);               -> 199803

`PERIOD_DIFF(A, B)'
     Returns months between periods `A' and `B'. `A' and `B' should be
     of format `YYMM' or `YYYYMM'.
          mysql> select PERIOD_DIFF(9802,199703);         -> 11

`DATE_ADD(date, INTERVAL expr TYPE), DATE_SUB(date, INTERVAL expr TYPE)'
     Adds or subtracts an intervall expression from a datetime or date
     column.  TYPE should be one of the following keywords This is new
     for *MySQL* 3.22.       SECOND        Seconds.                                               
     MINUTE        Minutes                                                
     HOUR          Hours                                                  
     DAY           Days                                                   
     MONTH         Months                                                 
     YEAR          Years                                                  
     MINUTE_SECOND Minutes and seconds in format "MINUTES:SECONDS"        
     HOUR_MINUTE   Hours and minutes in format "HOURS:MINUTES"            
     DAY_HOUR      Days and hours in format "DAYS HOURS"                  
     YEAR_MONTH    Years and months in format "YEARS-MONTH"               
     HOUR_SECOND   Hours, minutes and seconds in format                   
                   "HOUR:MINUTES:SECONDS"                                 
     DAY_MINUTE    Days, Hours and minutes in format "DAYS HOUR:MINUTES"  
     DAY_SECOND    Days, Hours, minutes and seconds in format "DAYS       
                   HOUR:MINUTES:SECONDS"                                  



     *MySQL* allows any separator in the format, the above are the
     suggested formats. The expr is a string that may start with a `-'
     for negative intervals.  If the date is a date column and one only
     uses calculation with YEAR, MONTH and DAY then the result is a
     DATE, else it's a DATETIME. If one uses wrong dates or interval of
     wrong type the result is NULL.

     date_add("1997-12-31 23:59:59",INTERVAL  1998-01-01 00:00:00  
     1 SECOND)                                                     
     date_add("1997-12-31 23:59:59",INTERVAL  1998-01-01 00:01:00  
     "1:1" MINUTE_SECOND)                                          
     date_sub("1998-01-01 00:00:00",INTERVAL  1997-12-30 22:58:59  
     "1 1:1:1" DAY_SECOND)                                         
     select date_add("1997-12-31              1998-01-01 23:59:59  
     23:59:59",INTERVAL 1 DAY)                                     
     date_add("1998-01-01 00:00:00",INTERVAL  1997-12-30 14:00:00  
     "-1 10" DAY_HOUR)                                             
     date_sub("1998-01-02",INTERVAL 31 DAY)   1997-12-02           

`TO_DAYS(Date)'
     Changes a `Date' to a daynumber (Number of days since year 0).
     `Date' may be a `DATE' string, a `DATETIME' string, a
     `TIMESTAMP([6 | 8 | 14])' or a number of format `YYMMDD' or
     `YYYYMMDD'.
          mysql> select TO_DAYS(9505);                    -> 733364
          mysql> select TO_DAYS('1997-10-07);             -> 729669

`FROM_DAYS()'
     Changes a daynumber to a DATE.
          mysql> select from_days(729669);                -> 1997-10-07

`DATE_FORMAT(Date, Format)'
     Formats the `Date' (a date or a timestamp) according to the
     `Format' string. The following format commands are known:      M       Month name                                                   
     W       Weekday name                                                 
     D       Day of the month with english suffix                         
     Y       Year with 4 digits                                           
     y       Year with 2 digits                                           
     a       Abbreviated weekday name (Sun..Sat)                          
     d       Day of the month, numeric                                    
     m       Month, numeric                                               
     b       Abbreviated month name (Jan.Dec)                             
     j       Day of year (001..366)                                       
     H       Hour (00..23)                                                
     k       Hour ( 0..23)                                                
     h       Hour (01..12)                                                
     I       Hour (01..12)                                                
     l       Hour ( 1..12)                                                
     i       Minutes, numeric                                             
     r       Time, 12-hour (hh:mm:ss [AP]M)                               
     T       Time, 24-hour (hh:mm:ss)                                     
     S       Seconds (00..59)                                             
     s       Seconds (00..59)                                             
     p       AM or PM                                                     
     w       Day of the week (0=Sunday..)                                 
     %       single % are ignored.  Use %% for a % (for future            
             extensions).                                                 



     All other characters are copied to the result.
          mysql> select date_format('1997-10-04 22:23:00', '%W %M %Y %h:%i:%s');
                  -> 'Saturday October 1997 22:23:00'
          mysql> select date_format('1997-10-04 22:23:00', '%D %y %a %d %m %b %j %H %k %I %r %T %S %w');
                  -> '4th 97 Sat 04 10 Oct 277 22 22 10 10:23:00 PM 22:23:00 00 6'

     For the moment `%' is optional.  In future versions of *MySQL* `%'
     will be required.

`TIME_FORMAT(time expr, format)'
     This can be used like the DATE_FORMAT above, but only with the
     format options which handle hours, minutes and seconds.  Other
     options give NULL value or 0.

`CURDATE()'
`CURRENT_DATE'
     Returns today's date. In form `YYYYMMDD' or `'YYYY-MM-DD''
     depending on whether `CURDATE()' is used in a number or string
     context.
          mysql> select CURDATE();                -> '1997-12-15'
          mysql> select CURDATE()+0;              -> 19971215

`CURTIME()'
`CURRENT_TIME'
     Returns the current time in the form `HHMMSS' or `'HH:MM:SS'',
     depending on whether `CURTIME()' is used in a number or string
     context.
          mysql> select CURTIME();                -> '23:50:20'
          mysql> select CURTIME()+0;              -> 235026

`NOW()'
`SYSDATE()'
`CURRENT_TIMESTAMP'
     Returns the current time. In format `YYYYMMDDHHMMSS' or
     `'YYYY-MM-DD HH:MM:SS'' depending on whether `NOW()' is used in a
     number or string context.
          mysql> select NOW();            -> '1997-12-15 23:51:26'
          mysql> select NOW()+0;          -> 19971215235131

`UNIX_TIMESTAMP([date expression])'
     If called without any arguments, a unix timestamp (seconds in GMT
     since 1970.01.01 00:00:00). Normally it is called with a
     `TIMESTAMP' column as an argument in which case it returns the
     columns value in seconds.  `Date' may also be a date string, a
     datetime string, or a number of format YYMMDD or YYYMMDD in local
     time.
          mysql> select UNIX_TIMESTAMP();                         -> 882226357
          mysql> select UNIX_TIMESTAMP('1997-10-04 22:23:00');    -> 875996580

`FROM_UNIXTIME(Unix_timestamp)'
     Returns a string of the timestamp in `YYYY-MM-DD HH:MM:SS' or
     `YYYYMMDDHHMMSS' format depending on context (numeric/string).
          mysql> select FROM_UNIXTIME(875996580);   -> '1997-10-04 22:23:00'

`FROM_UNIXTIME(Unix_timestamp, Format_string)'
     Returns a string of the timestamp formated according to the
     Format_string. The format string may contain:      `M'           Month, textual                                         
     `W'           Day (of the week), textual                             
     `D'           Day (of the month), numeric plus english suffix        
     `Y'           Year, numeric, 4 digits                                
     `y'           Year, numeric, 2 digits                                
     `m'           Month, numeric                                         
     `d'           Day (of the month), numeric                            
     `h'           Hour, numeric                                          
     `i'           Minutes, numeric                                       
     `s'           Seconds, numeric                                       
     `w'           Day (of the week), numeric                             
     All other     All other characters are just copied.                  



          mysql> select FROM_UNIXTIME(UNIX_TIMESTAMP(), 'Y D M h:m:s x');
                  -> '1997 23rd December 03:12:30 x'

`SEC_TO_TIME(Seconds)'
     Returns the hours, minutes and seconds of the argument in `H:MM:SS'
     or `HMMSS' format depending on context.
          mysql> select SEC_TO_TIME(2378);                -> '00:39:38'
          mysql> select SEC_TO_TIME(2378)+0;              -> 3938

`TIME_TO_SEC(Time)'
     Converts `Time' to seconds.
          mysql> select TIME_TO_SEC('22:23:00');  -> 80580
          mysql> select TIME_TO_SEC('00:39:38');  -> 2378

Miscellaneous functions
-----------------------

`DATABASE()'
     Returns current database name.
          mysql> select DATABASE();               -> 'test'

`USER()'
`SYSTEM_USER()'
`SESSION_USER()'
     Returns current user name.
          mysql> select USER();                   -> 'davida'

`PASSWORD(String)'
     Calculates a password string from plaintext password `String'. This
     must be used to store a password in the 'user' grant table.
          mysql> select PASSWORD('badpwd');       -> '7f84554057dd964b'

`ENCRYPT(String[, Salt])'
     Crypt `String' with the unix `crypt()' command. The `Salt' should
     be a string with 2 characters. If `crypt()' was not found `NULL'
     will always be returned.

`LAST_INSERT_ID()'
     Returns the last automatically generated value that was set in an
     auto_increment column. *Note mysql_insert_id::.
          mysql> select LAST_INSERT_ID();         -> 1

`FORMAT(Nr, Num)'
     Formats number `Nr' to a Format like '#,###,###.##' with `Num'
     decimals.
          mysql> select FORMAT(12332.33, 2);      -> '12,332.33'

`VERSION'
     Return the version of the *MySQL* server.
          mysql> select version();                -> '3.21.16-beta-log'

`GET_LOCK(String,timeout)'
     Tries to get a lock on named 'String' with a timeout of 'timeout'
     seconds.  Returns 1 if one got the lock, 0 on timeout and NULL on
     error (like out of memory or if thread was killed with `mysqladmin
     kill'.  A lock is released if one executes `RELEASE_LOCK',
     executes a new `GET_LOCK' or if the thread ends.  This function
     can be used to implement application locks or simulate record
     locks.
          mysql> select get_lock("automatically released",10);   -> 1
          mysql> select get_lock("test",10);		       -> 1
          mysql> select release_lock("test");                    -> 1
          mysql> select release_lock("automatically released")   -> NULL

`RELEASE_LOCK(String)'
     Releases a lock this thread has got with `GET_LOCK'. Returns 1 if
     the lock was released, 0 if lock wasn't locked by this thread and
     NULL if the lock 'String' didn't exist.

Functions for `GROUP BY' clause
-------------------------------

`COUNT(Expr)'
     Count number of non `NULL' rows. `count(*)' is optimised to return
     very quickly if no other column is used in the `SELECT'.
          select count(*) from student;
          select count(if(length(name)>3,1,NULL)) from student;

`AVG(expr)'
     Average value of expr.

`MIN(expr)'
`MAX(expr)'
     Minimum/Maximum value of expr. `min()' and `max()' may take a
     string argument and will then return the minimum/maximum string
     value.

`SUM(expr)'
     Sum of expr.

`STD(expr)'
`STDDEV(expr)  (Oracle format)'
     Standard derivative of expression. This is a extension to `ANSI
     SQL'.

`BIT_OR(expr)'
     The bitwise `OR' of all bits in expr. Calculation done with 64 bit
     precision.

`BIT_AND(expr)'
     The bitwise `AND' of all bits in expr. Calculation done with 64
     bit precision.

   *MySQL* has extended the use of `GROUP BY'. You can use columns or
calculations in the `SELECT' expressions which don't appear in the
`GROUP BY' part. This stands for *any possible value for this group*.
By using this, one can get a higher performance by avoiding sorting and
grouping on unnecessary items.  For example, in the following query one
doesn't need to group on b.name:

     SELECT a.id,b.name,COUNT(*) from a,b WHERE a.id=b.id GROUP BY a.id

   In ANSI SQL you would have to add the customer.name in the `GROUP BY'
for the following query. In *MySQL* the name redundant.

     SELECT order.custid,customer.name,max(payments) from order,customer
     WHERE order.custid = customer.custid GROUP BY order.custid;

   Don't use this feature if the columns you leave out from the `GROUP
BY' part isn't unique in the group!

   In some specific cases you can use MIN() and MAX() to get a specific
column even it isn't unique. The following gives the value from the row
with the smallest 'sort' value.

     SUBSTR(MIN(concat(sort,space(6-length(sort)),column),7,length(column)))

   Note that you can't yet use expressions in the `GROUP BY' or `ORDER
BY' clause.  You can on the other hand use an alias on an expression
and use this to solve the problem:

     SELECT id,FLOOR(value/100) AS val FROM table_name GROUP BY id,val ORDER BY val

Create database syntax
======================

     CREATE DATABASE database_name

   Creates a database with the given name. The name can only contain
letters, numbers or the `'_'' character and must start with a letter or
a `_'.  The maximum length of a database name is 64 characters.  All
databases in *MySQL* are directories, so a CREATE DATABASE only creates
a directory in the *MySQL* database directory.  You can also create
databases with `mysqladmin'.  *Note Programs::

Drop database syntax
====================

     DROP DATABASE [IF EXISTS] database_name

   Drop all tables in the database and deleted the database.  *You have
to be VERY carefull with this command!* `DROP DATABASE' returns how
many files was removed from the directory.  Normally this is number of
tables*3.  You can also drop databases with `mysqladmin'.  *Note
Programs::

   In *MySQL* 3.22 one can use the new keywords `IF EXISTS' to not get
an error for a database that doesn't exits.

CREATE TABLE syntax
===================

     CREATE TABLE table_name ( create_definition,... )
     
     create_definition:
       column_name type [NOT NULL | NULL] [DEFAULT default_value] [AUTO_INCREMENT]
                        [ PRIMARY KEY ] [reference_definition]
       or	PRIMARY KEY ( index_column_name,... )
       or	KEY [index_name] KEY( index_column_name,...)
       or	INDEX [index_name] ( index_column_name,...)
       or	UNIQUE [index_name] ( index_column_name,...)
       or    FOREIGN KEY index_name ( index_column_name,...) [reference_definition]
       or	CHECK (expr)
     
     type:
             TINYINT[(length)] [UNSIGNED] [ZEROFILL]
       or    SMALLINT[(length)] [UNSIGNED] [ZEROFILL]
       or    MEDIUMINT[(length)] [UNSIGNED] [ZEROFILL]
       or    INT[(length)] [UNSIGNED] [ZEROFILL]
       or    INTEGER[(length)] [UNSIGNED] [ZEROFILL]
       or    BIGINT[(length)] [UNSIGNED] [ZEROFILL]
       or    REAL[(length,decimals)] [UNSIGNED] [ZEROFILL]
       or    DOUBLE[(length,decimals)] [UNSIGNED] [ZEROFILL]
       or	FLOAT[(length,decimals)] [UNSIGNED] [ZEROFILL]
       or	DECIMAL[(length,decimals)] [UNSIGNED] [ZEROFILL]
       or	NUMERIC[(length,decimals)] [UNSIGNED] [ZEROFILL]
       or    CHAR(length) [BINARY],
       or    VARCHAR(length) [BINARY],
       or    DATE
       or    TIME
       or    TIMESTAMP
       or    DATETIME
       or    TINYBLOB
       or    BLOB
       or    MEDIUMBLOB
       or    LONGBLOB
       or    TINYTEXT
       or    TEXT
       or    MEDIUMTEXT
       or    ENUM(value1,value2,value3...)
       or    SET(value1,value2,value3...)
     
     index_column_name:
             column_name [ (length) ]
     
     reference_definition:
             REFERENCES table_name [( index_column_name,...)]
                        [ MATCH FULL | MATCH PARTIAL]
                        [ ON DELETE reference_option]
                        [ ON UPDATE reference_option]
     
     reference_option:
             RESTRICT | CASCADE | SET NULL | NO ACTION | SET DEFAULT
   *Note Column types::

   The FOREIGN KEY, CHECK and REFERENCE syntax are only for
compatibility.  (To make it easier to port code from other SQL servers
and run applications that create tables with references). They don't
actually do anything.  *Note Missing functions::

   If a column doesn't have a DEFAULT value and is not declared as NOT
NULL, the default value is NULL.

   If a column doesn't have a DEFAULT value and is declared as NOT NULL,
*MySQL* will automatically assign a default value for the field.

   * ZEROFILL means that number is pre-zeroed to maximal length. With
     `INT(5) ZEROFILL' a value of 5 is retrieved as `00005'.

   * `BINARY' means that the column will be compared case sensitive. The
     default is that all strings are compared case insensitive
     according to ISO-8859-1 Latin1. `BINARY' is 'sticky' which means
     that if a column marked `BINARY' is used in a expression, the
     whole expression is compared `BINARY'.

   * KEY is a synonym for INDEX.

   * UNIQUE is in *MySQL* a key that can only have distinct values. You
     will get an error if you try add a new row with a key that matches
     an old row.

   * PRIMARY KEY is a unique KEY.  One can only have one PRIMARY KEY in
     a table.

   * If one doesn't assign a name to an index, the index will get the
     same name as the first key_column with an optional _# to make it
     unique.

   * Index columns and timestamp columns can't be NULL. For these
     columns the NULL attribute is silently removed.

   * With `column_name(length)' syntax one can specify an index which
     is only a part of a `string' column. This can make the index file
     much smaller.

   * A number column may have the additional attribute AUTO_INCREMENT
     to automatically get the largest value+1 for each insert where
     column value is NULL or 0. *Note mysql_insert_id::

   * One can insert NULL for timestamp and auto_increment columns. This
     results in the current time / the next number.

   * Blob columns can't be index.

   * When one groups on a blob only the first 'max_sort_length' bytes
     are used. *Note BLOB Limitations::.

   * Deleted records are in a linked list and subsequent inserts will
     reuse old positions. To get smaller files one can use the
     `isamchk' utility to reorganise tables.

   * Each null column takes one bit extra, rounded up to the nearest
     byte.

   * The maximum record length can be calculated as follows: 1+
     sum_of_column_lengths + null_columns/8 + number of variable length
     columns.

   * In some cases an attribute may silently change after creation:
     `VARCHAR' columns with a length of one or two are changed to
     `CHAR'. When using one `VARCHAR' column all `CHAR' columns longer
     than 3 are changed to `VARCHAR''s.  This doesn't affect the usage
     of the column in any way; In *MySQL* `VARCHAR' is just a different
     way to store characters.  `MySQL' does the conversion because it
     will save space and make the table faster.  *Note Row format::

   * On `INSERT'/`UPDATE' all strings (`CHAR' and `VARCHAR') are
     silently chopped/padded to the maximal length given by CREATE. All
     end spaces are also automatically removed. For example
     `VARCHAR(10)' means that the column can contain strings with a
     length up to 10 characters.

   * Something/0 gives a `NULL' value.

   * The regular expression function (`REGEXP' and `RLIKE') uses
     ISO8859-1 (Latin1) when deciding the type of a character.

ALTER TABLE syntax
==================

     ALTER [IGNORE] TABLE table_name alter_spec [, alter_spec ...]
     
     alter_specification:
     	ADD [COLUMN] create_definition [AFTER column_namn | FIRST]
     or	CHANGE [COLUMN] old_column_name create_definition
     or	ALTER [COLUMN] column_name { SET DEFAULT literal | DROP DEFAULT }
     or	ADD INDEX [index_name] ( index_column_name,...)
     or	ADD UNIQUE [index_name] ( index_column_name,...)
     or	DROP [COLUMN] column_name
     or	DROP PRIMARY KEY
     or	DROP INDEX key_name
     or	RENAME [AS] new_table_name

   * `ALTER TABLE' works by creating a temporary table and copying all
     information to it and then the old table is deleted and the new
     one is renamed. This is done in such a way that all updates are
     automatically redirect to the new table without any failed
     updates. While the `ALTER TABLE' is working, the old table is
     readable for other clients. Table updates/writes to the table are
     stalled and only executed after the new table is ready.

   * If `IGNORE' isn't specified then the copy will be aborted and
     rolled back if there exists any duplicated unique keys in the new
     table. In case of duplicates the first found row will be used.
     This is a *MySQL* extension.

   * The `CHANGE column_name', `DROP column_name' and `DROP INDEX' are
     *MySQL* extensions to ANSI SQL92.

   * The optional word `COLUMN' is a pure noise word and can be omitted.

   * The `ADD' and `CHANGE' takes the same create_definition as `CREATE
     TABLE'. *Note Create table::.

   * In *MySQL* 3.22 you can use `ADD' ... `AFTER' column_namn or
     `FIRST' to add a column at some specific location in your table.
     The default is the add the column last.

   * `ALTER COLUMN' sets a new default value or removes the old default
     value for a column.

   * `DROP INDEX' removes an index. This is a *MySQL* extension.

   * The `FOREIGN KEY' syntax in *MySQL* exists only for compatibility.
     *Note Missing functions::

   * If one drops a column_name which is part of some index, this index
     part is removed. If all index parts are removed then the index is
     removed.

   * `DROP PRIMARY KEY' drops index named `PRIMARY' or if no such index
     exists, it drops the first `UNIQUE' index in the table.

   * `CHANGE' tries to convert data to the new format as good as
     possible.

   * With `mysql_info(MYSQL*)' one can retrieve how many records were
     copied and how many records were deleted because of multiple
     indexes.

   * To use `ALTER TABLE' one needs select, insert, delete, update,
     create and drop privileges on the table.

   * If one uses `ALTER TABLE table_name RENAME AS new_name' without any
     other options, *MySQL* will only do a fast rename of table table.

   Some examples of using ALTER TABLE:

     CREATE TABLE t1 (a INTEGER,b CHAR(10));
     INSERT INTO t1 VALUES(1,"testing");
     ALTER TABLE t1 RENAME t2;
     ALTER TABLE t2 CHANGE a a TINYINT NOT NULL, CHANGE b c CHAR(20);
     ALTER TABLE t2 ADD d TIMESTAMP;
     ALTER TABLE t2 ADD INDEX (d), ADD PRIMARY KEY (a);
     ALTER TABLE t2 DROP COLUMN c;
     ALTER TABLE t2 ADD c INT UNSIGNED NOT NULL AUTO_INCREMENT, ADD INDEX (c);
     DROP TABLE t2;

DROP TABLE syntax
=================

   `DROP TABLE [IF EXISTS] table_name [, table_name...]'

   Removes one or more tables. All the data and the definition are
*removed* so take it easy with this command!

   In *MySQL* 3.22 one can use the new keywords `IF EXISTS' to not get
an error for tables that doesn't exits.

DELETE syntax
=============

   `DELETE FROM table_name WHERE where_definition'

   Returns records affected.

   If one does a delete without a `WHERE' clause then the table is
recreated, which is much faster than doing a delete for each row. In
these cases, the command returns zero as affected records. *MySQL*
can't return the number of deleted row because the recreate is done
without opening the data files to make sure that one can recreate the
table as long as the table definition file `table_name.frm' is valid.

SELECT syntax
=============

   `SELECT [STRAIGHT_JOIN] [DISTINCT | ALL] select_expression,... [INTO
OUTFILE 'file_name' ...] [ FROM table_references [WHERE
where_definition ] [GROUP BY column,...] [HAVING where_definition] [
ORDER BY column [ASC | DESC] ,..] [LIMIT [offset,] rows] [PROCEDURE
procedure_name]] '

   All used keywords must come in exactly the above order. For example
a `HAVING' clause must come after any `GROUP BY' and before any `ORDER
BY' clause.

   Strings are automatically converted to numbers and numbers to strings
when needed (a-la Perl). If in a compare operation (`(=, <>, <= ,<, >=,
>)') either of the arguments are numerical, the arguments are compared
as numbers, else the arguments are compared as strings. All string
comparisons are by default done case-independent by ISO8859-1 (The
Scandinavian letter set which also works excellently with English).

     select 1 > '6x';        ->      0
     
     select 7 > '6x';        ->      1
     
     select 0 > 'x6';        ->      0
     
     select 0 = 'x6';        ->      1

   - A column name does not need a table prefix if the given column name
     is unique.

   - A select expression may be given an alias which will be its column
     name and can be used when sorting and grouping or in the `HAVING'
     clause.
          select concat(last_name,' ',first_name) as name from table order by name

   - Table_references is a list of tables to join. This may also contain
     `LEFT OUTER JOIN' references.  *Note Join::

   - In `LIKE' expressions % and _ may be preceded with '\' to skip the
     wildcard meaning and get a literal % or _.

   - A DATE is a string with one of the following syntaxes:
        - YYMMDD        (Year is assumed to be 2000 if YY < 70.)

        - YYYYMMDD

        - YY.MM.DD	Where '.' may be any non-numerical separator.

        - YYYY.MM.DD	Where '.' may be any non-numerical separator.

   - `IFNULL()' and `IF()' return number or string value according to
     use.

   - `ORDER' and `GROUP' columns may be given as column names, column
     aliases or column numbers in `SELECT' clauses.

   - The `HAVING' clause can take any column or alias in the
     select_expressions. It is applied last, just before items are sent
     to the client, without any optimisation. Don't use it for items
     that should be in the WHERE clause. You can't write (yet):

          `SELECT user,MAX(salary) FROM users GROUP BY user HAVING max(salary)>10'

     Change it to:

          `SELECT user,MAX(salary) AS sum FROM users GROUP BY user HAVING sum > 10'

   - `STRAIGHT_JOIN' forces the optimiser to join the tables in the same
     order that the tables are given in the `FROM' clause. One can use
     this to get a query to be done more quickly if the optimiser joins
     the tables in non-optimal order. *Note Explain::

   - LIMIT takes one or two numerical arguments.
        * If one argument, the argument indicates the maximum number of
          rows in a result.

        * If two arguments, the first argument says the offset to the
          first row to return, the second is the maximum number of rows.

   - INTO OUTFILE 'filename' writes the given set to a file. The file
     can not already exist from before. *Note Load::.

Join syntax
===========

   *MySQL* supports the following `JOIN' syntaxes:

     table_reference, table_reference
     table_reference [CROSS] JOIN table_reference
     table_reference STRAIGHT_JOIN table_reference
     table_reference LEFT [OUTER] JOIN table_reference ON conditional-expr
     table_reference LEFT [OUTER] JOIN table_reference USING (column-commalist)
     table_reference NATURAL LEFT [OUTER] JOIN table_reference
     { oj table_reference LEFT OUTER JOIN table_reference ON conditional-expr }

   The last version is ODBC syntax.

   * A table reference may be aliased with `table_reference AS alias' or
     `table_reference alias'.

   * `,' and `JOIN' are semantically identical.  This does a full join
     between the used tables.  One normally specifies in the `WHERE'
     condition how the tables should be linked.

   * The `ON' conditional is any `WHERE' conditional.  If there is no
     matching record for the right table in a `LEFT JOIN' a row with all
     columns set to NULL will be used for the right table.

   * The `USING' column-list is a list of fields that must exists in
     both tables.  `A LEFT JOIN B USING (C1,C2,C3...)' is defined to be
     semantically identical to using an `ON' expression ` A.C1=B.C1 AND
     A.C2=B.C2 AND A.C3=B.C3... '.

   * The `NATURAL LEFT JOIN' of two tables is defined to be semantically
     identical to a `USING' with all column names that exist in both
     tables.

   * The last `LEFT JOIN' syntax exists only for compatibility with
     ODBC.

   * STRAIGHT_JOIN is identical as JOIN, except that the left table
     will always be read before the right table. This can be used in
     the few cases when the join optimizer puts the tables in the wrong
     order.

   Some examples:

     SELECT * from table1,table2 where table1.id=table2.id;
     SELECT * from table1 LEFT JOIN table2 ON table1.id=table2.id;
     SELECT * from table1 LEFT JOIN table2 USING (id);
     SELECT table1.* from table1 LEFT JOIN table2 ON table1.id=table2.id WHERE table2.id IS NULL;
     SELECT * from table1 LEFT JOIN table2 ON table1.id=table2.id LEFT JOIN table3 ON table3.id=table2.id;

   The fourth example is noteworthy as it finds all rows in table1 that
doesn't have an row in table2.

INSERT syntax
=============

     	INSERT INTO table [ (column_name,...) ] VALUES (expression,...)
     or	INSERT INTO table [ (column_name,...) ] SELECT ...

   An expression may use any previous column in column_name list (or
table if no column name list is given).

   The following holds for a multi-row `INSERT' statement:
   - The query cannot contain an `ORDER BY' clause.

   - The target table of the `INSERT' statement cannot appear in the
     FROM clause of the query.

   - If one uses `INSERT INTO ... SELECT ...' then one can get the
     following info string with the C API function `mysql_info()'.

     `Records: 100 Duplicates: 0 Warnings: 0' Duplicates are rows which
     couldn't be written because some index would be duplicated.
     Warnings are columns which were set to NULL, but have been
     declared NOT NULL. These will be set to their default value.

     In this case it's also forbidden in ANSI SQL to SELECT from the
     same table that you are inserting into. The problem that there may
     be problems if the SELECT finds records that is inserted at the
     same run.  When using sub selects the situation could easily be
     very confusing!

   - If one sets a time stamp value to anything other than NULL, the
     time stamp value will be copied to the result table.

   - Auto increment columns works as usual.

REPLACE syntax
==============

     	REPLACE INTO table [ (column_name,...) ] VALUES (expression,...)
     or	REPLACE INTO table [ (column_name,...) ] SELECT ...

   This works exactly like `INSERT', except that if there was some old
record in the table with the same unique index the old record or records
will be deleted before this record is inserted.  *Note Insert::.

LOAD DATA INFILE syntax
=======================

   `LOAD DATA INFILE' 'text_file_name.text' [`REPLACE' | `IGNORE']
`INTO' `TABLE' table_name [`FIELDS' [`TERMINATED BY' ',' [`OPTIONALLY']
`ENCLOSED BY' '"' `ESCAPED BY' '\\' ]] [`LINES TERMINATED BY' '\n']
[(Field1, Field2...)]

   This is used to read rows from a text file, which must be located on
the server, at a very high speed. The server-client protocol doesn't yet
support files over a connection. If you only have the file on the
client, use *rcp* or *ftp* to copy it, possibly compressed, to the
server before using `LOAD DATA INFILE'. All paths to the text file are
relative to the database directory.

   To write data to a text file, use the `SELECT ... INTO OUTFILE
'interval.txt' fields terminated by ',' enclosed by '"' escaped by '\\'
lines terminated by '\n' FROM ...'  syntax.

   Normally you don't have to specify any of the text file type
options. The default is a compact text file with columns separated with
`tab' characters and all rows end with a newline. Tabs, newlines and `\'
inside fields are prefixed with a `\'. NULLs are read and written as \N.

   `FIELDS TERMINATED BY' has the default value of `\t'.

   `FIELDS [OPTIONALLY] ENCLOSED BY' has the default value of `'''.

   `FIELDS ESCAPED BY' has the default value of `'\\''.

   `LINES TERMINATED BY' has the default value of `'\n''.

   `FIELDS TERMINATED BY' and `LINES TERMINATED BY' may be more than
one character.

   If `LINES TERMINATED BY' is an empty string and `FIELDS TERMINATED
BY' is non-empty then lines are also terminated with `FIELDS TERMINATED
BY'.

   If `FIELDS TERMINATED BY' and `FIELDS ENCLOSED BY' both are empty
strings (`''') then this gives a fixed row format ("not delimited"
import format). With a fixed row size NULL values are output as a blank
string.

   If you specify `OPTIONALLY' in `ENCLOSED BY', then only strings are
enclosed in `ENCLOSED BY' by the `SELECT ... INTO' statement.

   Duplicated `ENCLOSED BY' chars are removed from strings that start
with `ENCLOSED BY'. For example: With `ENCLOSED BY '"'':
     "The ""BIG"" boss"  -> The "BIG" boss
     The "BIG" boss	    -> The "BIG" boss

   If `ESCAPED BY' is not empty then the following characters will be
prefixed with the escape character: `ESCAPED BY', `ASCII 0', and the
first character in any of `FIELDS TERMINATED BY', `FIELDS ENCLOSED BY'
and `LINES TERMINATED BY'.

   If `FIELDS ENCLOSED BY' is not empty then `NULL' is read as a `NULL'
value. If `FIELDS ESCAPED BY' is not empty then `\N' is also read as a
`NULL' value.

   If `REPLACE' is used, then the new row will replace all rows which
have the same unique index. If `IGNORE' is used, the row will then be
skipped if a record already exists with an identical unique key.  If
none of the above options are used an error will be issued. The rest of
the text file will be ignored if one gets a duplicate index error.

   Some possible cases that are not supported by `LOAD DATA':
   * Fixed size rows (`FIELDS TERMINATED BY' and `FIELDS ENCLOSED BY'
     both are empty) and BLOB columns.

   * If some of the separators are a prefix of another.

   * `FIELDS ESCAPED BY' is empty and the data contains `LINES
     TERMINATED BY' or `FIELDS ENCLOSED BY' followed by `FIELDS
     TERMINATED BY'.

   All rows are read into the table. If a row has too few columns, the
rest of the columns are set to default values. `TIMESTAMP' columns are
only set to the current time if there is a NULL value for the column or
if the `TIMESTAMP' column is left out from the field list when the field
list is used (the last case only holds for the first `TIMESTAMP'
column).

   For security reasons the text file must either reside in the database
directory or be readable by all. Each user that wants to use `LOAD DATA
INFILE' must also have 'Y' in the 'File_priv' column in the user
privilege table!  *Note Privileges::

   Because `LOAD DATA INFILE' regards all input as strings you can't use
number values for `enum' or `set' columns as you can with `INSERT'
statements.  All `enum' and `set' must be given as strings!

   For more information about the escaped syntax, *Note Base Syntax::.

   When the `LOAD DATA' query is done, one can get the following info
string with the C API function `mysql_info()'.

   `Records: 1  Deleted: 0  Skipped: 0  Warnings: 0'

   Warnings are incremented for each column which can't be stored
without loss of precision, for each column which didn't get a value
from the read text line (happens if the line is too short) and for each
line which has more data than can fit into the given columns.  A warning
is also given for any time, date, timestamp or datetime column that is
set to 0.

   An example that loads all columns:

     LOAD DATA INFILE 'persondata.text' INTO TABLE persondata;

   *Note Table efficiency::

UPDATE syntax
=============

     UPDATE table SET column=expression,... WHERE where_definition

   All updates are done from left to right. If one accesses a column in
the expression, update will then use the current value (a given value
or the default value) of the column.

     UPDATE persondata SET count=count+1

   A `UPDATE' statements returns how many rows was actually changed.
In *MySQL* 3.22 `mysql_info()' returns the number of rows that was
matched and updated and how warnings one got during the update.

SHOW syntax. Get information about tables, columns...
=====================================================

     	SHOW DATABASES [LIKE wild]
     or 	SHOW TABLES [FROM database] [LIKE wild]
     or	SHOW COLUMNS FROM table [FROM database] [LIKE wild]
     or	SHOW INDEX FROM table [FROM database]
     or	SHOW STATUS
     or	SHOW VARIABLES [LIKE wild]

   Gives information about databases, tables or columns. If the `LIKE
wild' part is used the `wild' string is a normal SQL wildcard (with %
and _). `FIELDS' may be used as an alias for `COLUMNS' and `KEYS' may
be used as an alias for `INDEXES'.

   `STATUS' gives status information from the server like `mysqladmin
status'). The output may differ from the following:

`Uptime'           `Running_threads'  `Questions'        `Reloads'          `Open_tables'      
119                1                  4                  1                  3                  

   `VARIABLES' shows the values of the some of *MySQL* system
variables. Most of these variables can be changed by different options
to `mysqld'!

EXPLAIN syntax. Get information about a SELECT
==============================================

     	EXPLAIN SELECT select_options

   Gives information about how and in which order tables are joined.
With the help of `EXPLAIN' one can see when one has to add more indexes
to tables to get a faster select that uses indexes to find the records.
You can also see if the optimiser joins the tables in an optimal order.
One can force the optimiser to use a specific join order with the
`STRAIGHT_JOIN' option to select.

   The different join types are:

`system'
     The table has only one record (= system table)

`const'
     The table has at most one matching record which will be read at
     the start of the query. All columns in this table will be regarded
     as constants by the rest of the optimiser.

`eq_ref'
     One record will be read from this table for each combination of
     the previous tables.

`ref'
     All rows with matching indexes will be read from this table for
     each combination of the previous tables.

`range'
     Only rows that is in a given index range will be retrieved trough
     an index.  The extra column will tell which index is used.

`all'
     A full table scan will be done for each combination of the
     previous tables.

   Here is a example of a join which is optimised with the help of
`EXPLAIN'.

     EXPLAIN SELECT tt.TicketNumber, tt.TimeIn,
             tt.ProjectReference, tt.EstimatedShipDate,
             tt.ActualShipDate, tt.ClientID,
             tt.ServiceCodes, tt.RepetitiveID,
             tt.CurrentProcess, tt.CurrentDPPerson,
             tt.RecordVolume, tt.DPPrinted, et.COUNTRY,
             et_1.COUNTRY, do.CUSTNAME
             FROM tt, et, et AS et_1,
             do
             WHERE tt.SubmitTime Is Null and tt.ActualPC =
             et.EMPLOYID and tt.AssignedPC =
             et_1.EMPLOYID and tt.ClientID =
             do.CUSTNMBR;

   The `EXPLAIN' returns the following:

     table   type    possible_keys   key     key_len ref     rows    Extra
     et      ALL     PRIMARY NULL    NULL    NULL    74
     do      ALL     PRIMARY NULL    NULL    NULL    2135
     et_1    ALL     PRIMARY NULL    NULL    NULL    74
     tt      ALL     AssignedPC,ClientID,ActualPC    NULL    NULL    NULL   3872
             range checked for each record (key map: 35)

   In this case *MySQL* is doing a full join for all tables! This will
take quite a long time as the product of the number of rows in each
table must be examined! So if all tables had 1000 records *MySQL* has
to look at 1000^4 = 1000000000000 rows. If the tables are bigger you
can only imagine how long it would take...

   In this case the first error is that *MySQL* can't yet use
efficiently indexes on columns that are declared differently: (varchar()
and char() are not different in this context)

   In this case `tt.ActualPC' is `char(10)' and `et.EMPLOYID' is
`char(15)'.

   Fix:

     mysql> alter table tt change ActualPC ActualPC varchar(15);

   And the above explanation shows:

     table   type    possible_keys   key     key_len ref     rows    Extra
     tt      ALL     AssignedPC,ClientID,ActualPC    NULL    NULL    NULL   3872
             where used
     do      ALL     PRIMARY NULL    NULL    NULL    2135
             range checked for each record (key map: 1)
     et_1    ALL     PRIMARY NULL    NULL    NULL    74
             range checked for each record (key map: 1)
     et     eq_ref  PRIMARY PRIMARY 15      tt.ActualPC    1

   Which is not perfect but much better. This version is executed in a
couple of seconds.

   After

     mysql> alter table tt change AssignedPC AssignedPC varchar(15),
                           change ClientID Clientid     varchar(15);

   You get the following from `EXPLAIN':

     table   type    possible_keys   key     key_len ref     rows    Extra
     et      ALL     PRIMARY NULL    NULL    NULL    74
     tt      ref     AssignedPC,ClientID,ActualPC    ActualPC        15
             et.EMPLOYID   52      where used
     et_1    eq_ref  PRIMARY PRIMARY 15      tt.AssignedPC  1
     do      eq_ref  PRIMARY PRIMARY 15      tt.Clientid    1

   Which is 'almost' as good as it can get.  The problem is that
*MySQL* assumes that `tt.AcutalPC' is evenly distributed which isn't
the case in the tt.

   Fortunately it is easy to tell *MySQL* about this:

     shell> isamchk --analyze PATH_TO_MYSQL_DATABASE/tt
     shell> mysqladmin refresh

   And now the join is 'perfect':

     table   type    possible_keys   key     key_len ref     rows    Extra
     tt      ALL     AssignedPC,ClientID,ActualPC    NULL    NULL    NULL
             3872     where used
     et      eq_ref  PRIMARY PRIMARY 15      tt.ActualPC    1
     et_1    eq_ref  PRIMARY PRIMARY 15      tt.AssignedPC  1
     do      eq_ref  PRIMARY PRIMARY 15      tt.Clientid    1

DESCRIBE syntax. Get information about columns
==============================================

   `(DESCRIBE | DESC) table [column]'

   Gives information about columns. This command is for Oracle
compatibility. *Note Show::. Column may be a column name or a string.
Strings may contain wild cards.

`LOCK TABLES' syntax
====================

     LOCK TABLES table_name [AS alias] READ|WRITE [, table_name READ|WRITE]
     ...
     UNLOCK TABLES

   Locks tables for this thread. If a thread has a READ lock on a table,
the thread (and all other threads) can only read from the table. If a
thread has a WRITE lock one a table, then only this thread can READ and
WRITE on the table. All threads waits until they get all locks (no
timeouts).

   When one uses `LOCK TABLES' one must lock all tables one is going to
use!  This policy ensures that table locking is deadlock free.

     LOCK TABLES trans READ, customer AS c WRITE
     SELECT SUM(value) FROM trans WHERE customer_id= #some_id#;
     UPDATE customer SET total_value=#value_from_last_statement# WHERE
     customer_id=#some_id#
     UNLOCK TABLES

   All tables are automatically unlocked when one issues another `LOCK
TABLES' or if the connection to the server is closed.

   Normally you don't have to lock tables. There is a couple of cases
when you would like to lock tables anyway:

   * If you are going to run many operations on a bunch of tables, its
     much faster to lock the tables you are going to use.  The downside
     is of course that no other thread can update a READ locked table
     and no other thread can read a WRITE locked table.

   * As `MySQL' doesn't support a transaction environment, you must use
     lock tables if you want to ensure that no other thread comes
     between a read and a update. For example the previous example
     requires `LOCK TABLES' to be safe!  If one didn't use `LOCK
     TABLES' there is a change that someone inserts a new 'trans' row
     between the SELECT and UPDATE statements.

   * By using incremental updates (`UPDATE customer set
     value=value+new_value') or the LAST_INSERT_ID() function you can
     avoid using `LOCK TABLES' in many cases.

   You can also solve some cases by using user level locks: GET_LOCK()
and RELEASE_LOCK().  These locks are saved in a hash table in the server
and implemented with pthread_mutex for high speed.  *Note Miscellaneous
functions::

SET OPTION syntax
=================

     SET [OPTION] SQL_VALUE_OPTION=value, ...

   The used options remain in effect for the whole current session.

   The different options are:

`SQL_SELECT_LIMIT=value'
     The maximum number of records to return in any select.  If a
     select has a limit clause it overrides this statement.  The
     default value for a new connection is 'unlimited'.

`SQL_BIG_TABLES= 0 | 1'
     If set to 1 then all temporary tables are stored on disk instead
     of in memory.  This will be a little slower, but one will not get
     the error `The table ### is full' for big selects that require a
     big temporary table.  The default value for a new connection is 0
     (use in memory temporary tables).

`SQL_BIG_SELECTS= 0 | 1'
     If set to 1 then *MySQL* will abort if a select is attempted that
     will probably take a very long time. This is useful when an
     erroneous `WHERE' statement has been issued. A big query is
     defined as a `SELECT' that will probably have to examine more than
     `max_join_size' rows.  The default value for a new connection is 0
     (which will allow all SELECT's).

`CHARACTER SET character_set_name | DEFAULT'
     This maps all strings from and to the client with the given
     mapping.  Currently the only option for character_set_name is
     `cp1251_koi8', but one can easily add new mappings by editing the
     file `mysql_source_directory/sql/convert.cc'.  One can restore the
     default mapping by using `DEFAULT' as the character_set_name.

`SQL_LOG_OFF= 0 | 1'
     If set to 1 then no logging will done to the standard log for this
     client if the client has process list privileges.  This doesn't
     affect the update log!

`TIMESTAMP= timestamp_value | DEFAULT'
     Set the time for this client.  This is used to get the original
     timestamp if one uses the update log to restore rows.

`LAST_INSERT_ID= #'
     Set the value to be returned from LAST_INSERT_ID(). This is stored
     in the update log when one uses LAST_INSERT_ID() in a command that
     updates a table.

GRANT syntax (Compatibility function)
=====================================

     GRANT (ALL PRIVILEGES | (SELECT, INSERT, UPDATE, DELETE,
      REFERENCES (column list), USAGE))
      ON table TO user,... [WITH GRANT OPTION]

   This command doesn't do anything. It is only in *MySQL* for
compatibility reasons. (To make it easier to port code from other SQL
servers).  Privileges in *MySQL* are handled with the *MySQL* grant
tables. *Note Privileges::

CREATE INDEX syntax (Compatibility function)
============================================

   `CREATE [UNIQUE] INDEX index_name ON table_name (
column_name[(length]),... )'

   This function doesn't do anything in *MySQL* version before version
3.22.  This is mapped to a `ALTER TABLE' call to create indexes.  *Note
Alter table::

   Normally one creates all INDEX at the same time with `CREATE TABLE'
*Note Create table::

   `(col1, col2)' creates a multiple index over the two columns.  The
index can be seen as a concatenation of the given columns.  If you in
`CREATE TABLE' use `INDEX(col1)', `INDEX(col2)' instead of
`INDEX(col1,col2)' you get two separate indexes instead of one multiple
index.

     SELECT * FROM table WHERE col1=# AND col2=#

   In a case of an index on `(col1,col2)' the right row(s) can be
fetched directly.  In a case of `(col1)', `(col2)' the optimizer decides
which index will find fewer rows and this index will be used to fetch
the rows.

   If the table has an index `(col1,col2,col3...)' the prefix of this
can be used by the optimiser to find the rows. This means that the
above gives you search capabilities on: `(col1)' and `(col1,col2)' and
`(col1,col2,col3)'...

   *MySQL* can't use a portion of an index to locate rows through an
index.

   With the definition `(col1,col2,col3)':

     SELECT * FROM table WHERE col1=#
     SELECT * FROM table WHERE col2=#
     SELECT * FROM table WHERE col2=# and col3=#

   only the first query will use indexes.

   *MySQL* will also use indexes if the `LIKE' argument is a constant
string that doesn't start with a wild character:

   The following will use indexes:

     SELECT * from table WHERE key_column like "Patrick%";
     SELECT * from table WHERE key_column like "Pat%_ck%";

   In the above cases only rows with `Patrick <= key_column < Patricl'
and `Pat <= key_column < Pau' will be considered.

   The following selects will not use indexes:
     SELECT * from table WHERE key_column like "%Patrick%";
     SELECT * from table WHERE key_column like other_column;

   With `column_name(length)' syntax one can specify an index which is
only a part of a `string' column. This can make the index file much
smaller.

     CREATE INDEX part_of_name ON customer (name(10))

   As it's quite normal that most names differs in the first 10
characters, the above definition should not slow down searches on
names, but it could save a lot of disk and even speed up inserts!

DROP INDEX syntax (Compatibility function)
==========================================

   `DROP INDEX index_name'

   This function doesn't do anything in `MySQL' before version 3.22.
This is mapped to a `ALTER TABLE' call to drop the `INDEX' or `UNIQUE'
definition.  *Note Alter table::

Comment syntax
==============

   *MySQL* supports the `# to end of line' and `/* multiple line */'
comment styles.

     select 1+1;	# This comment is to the end of line
     select 1 /* in-line-comment */ + 1;
     select 1+
     /*
     This will be ignored
     */
     1;

   *MySQL* doesn't support the `--' ANSI SQL style comments.  *Note
Missing comments::.

CREATE FUNCTION syntax
======================

     CREATE FUNCTION <function_name> RETURNS [string|real|integer]
            SONAME <name_of_shared_library>
     
     DROP FUNCTION <function_name>

   User definable functions (UDF) is way to extend *MySQL* with new
functions that works as native *MySQL* functions like `ABS()' and
`concat()'.  UDF's are written in C or C++ and require that dynamic
loading works on the operating system.  The source distribution includes
the file `udf_example.cc' that defines 5 new functions.

   The functions name, type and shared library is saved in the new
system table 'func' in the 'mysql' database.  To be able to create new
functions one must have write privilege for the database 'mysql'.  If
one starts *MySQL* with -skip-grant-tables, then UDF initialization
will also be skipped.

   Each defined function may have a xxxx_init function and a xxxx_deinit
function.  The init function should alloc memory for the function and
tell the main function about the max length of the result (for string
functions), number of decimals (for double functions) and if the result
may be a null value.

   If a function sets the 'error' argument to 1 the function will not be
called anymore and mysqld will return NULL for all calls to this
instanse of the function.

   All strings arguments to functions are given as string pointer +
length to allow handling of binary data.  Remember that all functions
must be thread safe. This means that one is not allowed to alloc any
global or static variables that changes!  If one needs memory one
should alloc this in the init function and free this on the __deinit
function.

   A dynamically loadable file should be compiled sharable (something
like: `gcc -shared -o udf_example.so myfunc.cc').  You can easily get
all switches right by doing: `cd sql ; make udf_example.o' Take the
compile line that make writes, remove the '-c' near the end of the line
and add -o udf_example.so to the end of the compile line.  The
resulting library (udf_example.so) should be copied to some dir
searched by ld, for example /usr/lib.

   Some notes about the example functions:

   * Function `metaphon' returns a metaphon string of the string
     argument.  This is something like a soundex string, but it's more
     tuned for English.

   * Function `myfunc_double' returns summary of codes of all letters
     of arguments divided by summary length of all its arguments.

   * Function `myfunc_int' returns summary length of all its arguments.

   * Function `lookup' returns the IP number for an hostname.

   * Function `reverse_lookup' returns the hostname for a IP number.
     The function may be called with a string "xxx.xxx.xxx.xxx" or four
     numbers.

   After the library is installed one must notify `mysqld' about the new
functions with the commands:

     CREATE FUNCTION metaphon RETURNS STRING SONAME "udf_example.so";
     CREATE FUNCTION myfunc_double RETURNS REAL SONAME "udf_example.so";
     CREATE FUNCTION myfunc_int RETURNS INTEGER SONAME "udf_example.so";
     CREATE FUNCTION lookup RETURNS STRING SONAME "udf_example.so";
     CREATE FUNCTION reverse_lookup RETURNS STRING SONAME "udf_example.so";

   Functions should be created only once.  The functions can be deleted
by:

     DROP FUNCTION metaphon;
     DROP FUNCTION myfunc_double;
     DROP FUNCTION myfunc_int;
     DROP FUNCTION lookup;
     DROP FUNCTION reverse_lookup;

   The `CREATE FUNCTION' and `DROP FUNCTION' update the `func' table.
All active function will be reloaded on every restart of server (if
-skip-grant-tables is not given).

Is *MySQL* picky about reserved words?
======================================

   A common problem stems from trying to create a table with column
names `timestamp' or `group', the names of datatypes and functions
built into *MySQL*.  You're allowed to do it (for example, `ABS' is an
allowed column name), but whitespace is not allowed between a function
name and the `'('' when using the functions whose names are also column
names.

   The following are explictly reserved words in *MySQL*. Most of them
(for example) `group', are forbidden by ANSI SQL92 as column and/or
table names. A few are because *MySQL* needs them and is (currently)
using a yacc parser:

`action'           `add'              `all'              `alter'            
`and'              `as'               `asc'              `auto_increment'   
`between'          `bigint'           `bit'              `binary'           
`blob'             `both'             `by'               `cascade'          
`char'             `character'        `change'           `check'            
`column'           `columns'          `create'           `data'             
`database'         `databases'        `date'             `datetime'         
`day'              `day_hour'         `day_minute'       `day_second'       
`dayofweek'        `dec'              `decimal'          `default'          
`delete'           `desc'             `describe'         `distinct'         
`double'           `drop'             `escaped'          `enclosed'         
`enum'             `explain'          `fields'           `float'            
`float4'           `float8'           `foreign'          `from'             
`for'              `full'             `grant'            `group'            
`having'           `hour'             `hour_minute'      `hour_second'      
`ignore'           `in'               `index'            `infile'           
`insert'           `int'              `integer'          `interval'         
`int1'             `int2'             `int3'             `int4'             
`int8'             `into'             `is'               `join'             
`key'              `keys'             `leading'          `left'             
`like'             `lines'            `limit'            `lock'             
`load'             `long'             `longblob'         `longtext'         
`match'            `mediumblob'       `mediumtext'       `mediumint'        
`middleint'        `minute'           `minute_second'    `month'            
`natural'          `numeric'          `no'               `not'              
`null'             `on'               `option'           `optionally'       
`or'               `order'            `outer'            `outfile'          
`partial'          `precision'        `primary'          `procedure'        
`privileges'       `read'             `real'             `references'       
`rename'           `regexp'           `repeat'           `replace'          
`restrict'         `rlike'            `select'           `set'              
`show'             `smallint'         `sql_big_tables'   `sql_big_selects'  
`sql_select_limit' `sql_log_off'      `straight_join'    `starting'         
`table'            `tables'           `terminated'       `text'             
`time'             `timestamp'        `tinyblob'         `tinytext'         
`tinyint'          `trailing'         `to'               `use'              
`using'            `unique'           `unlock'           `unsigned'         
`update'           `usage'            `values'           `varchar'          
`varying'          `varbinary'        `with'             `write'            
`where'            `year'             `year_month'       `zerofill'         

   The following symbols (from the table above) are disallowed by ANSI
SQL but allowed by *MySQL* as column/table names. This is because some
of these names are very natural names and a lot of people have already
used them.

   * ACTION

   * BIT

   * DATE

   * ENUM

   * NO

   * TEXT

   * TIME

   * TIMESTAMP

How safe/stable is *MySQL*
**************************

How stable is *MySQL*?
======================

   At TcX, *MySQL* has worked without any problems in our projects
since mid-1996. When released to a wider public we noticed that there
were some pieces of 'untested code' in *MySQL* that were quickly found
by the new user group who made queries in a different manner.  Each new
release has had fewer portability problems than the previous one, even
though they have all had a lot of new features, and we hope that it
will be possible to label one of the next releases 'stable'.

   Each release of *MySQL* has been usable and there have only been
problems when users start to use code from 'the gray zones'. Naturally,
outside users can't know what the gray zones are and I hope this section
will clarify those currently known.

   Here we will try to answer some of the more important questions that
seems to concern a lot of people and clarify some issues. This section
has been put together from the information that has come forward in the
mailing list which is very active in reporting bugs.

   How stable is *MySQL*? Can I depend on *MySQL* in this project?

   This is about the 3.21.x version of *MySQL*. All known and reported
bugs are fixed in the latest version with the exception of the bugs
listed in the BUGS file which are things that are 'design' related.

   *MySQL* is written in multiple layers and different independent
modules. Here is a list of the different modules and how tested each of
them are.

*The ISAM table handler. Stable*
     This is how all the data is stored. In all *MySQL* releases there
     hasn't been a single (reported) bug in this code. The only known
     way to get a corrupted table is to kill the server in the middle
     of an update and because all data is flushed to disk between each
     query even this is unlikely to destroy any data beyond rescue.
     There hasn't been a single bug report about lost data because of
     bugs in *MySQL* either.

*The parser and lexical analyser. Stable*
     There hasn't been a single reported bug in this system for a
     couple of months.

*The C client code. Stable*
     No known problems. In early 3.20 releases there were some
     limitations in the send/receive buffer size. In 3.21.x the
     send/receive buffer is now dynamic up to a default of 512K.

*mysql, mysqladmin and mysqlshow. Stable*
     The command line clients have had very few bugs.

*mysqldump and mysqlimport. Beta*
     Rewritten for 3.21.

*Basic SQL. Stable*
     The basic SQL function system and string classes and dynamic memory
     handling. Not a single reported bug on this system.

*Query optimiser. Gamma*
     Some changes in 3.21.

*Range optimiser. Alpha*
     Totally rewritten for 3.21.x

*Join optimizer. Gamma*
     Small changes for 3.21.

*GROUP BY, ORDER BY and related function COUNT(). Beta*
     Rewritten for 3.21 and throughly tested.

*Locking. Gamma*
     This is very system dependent. On some systems there are big
     problems using standard OS locking (fcntl).  In these case one
     should run the *MySQL* daemon with the `--skip-locking' flag.
     Known problems are some Linux systems and SunOS when using
     NFS-mounted file systems.

*Linux threads. Gamma*
     The only problem found is with the fcntl() call, which is fixed by
     using `--skip-locking'. Some people have reported lockup problems
     with the 0.5 release.

*Solaris 2.5+ pthreads. Stable*
     We use this for all our production work.

*MIT-pthreads (Other systems). Beta*
     No reported bugs since 3.20.15 and no known bugs since 3.20.16. On
     some system there is 'misfeature' where some operations are quote
     slow (a 1/20 second sleep is done between each query). Of course
     MIT-pthreads may slow down everything a bit, but for index based
     selects a select is usually done in one time frame so there
     shouldn't be a mutex locking/thread juggling.

*Other thread implementions. Alpha*
     The ports to other systems are still very new and may have bugs,
     either in *MySQL* but most often in the thread implementation
     itself.

*LOAD DATA..., INSERT ... SELECT. Stable*
     Some people have thought they have found bugs in this but have
     turned up being misunderstandings. So check the manual before
     reporting bugs!

*ALTER TABLE. Gamma*
     Partly rewritten for 3.21.

*mysqlperl. Stable*
     No bugs reported except a lot of compiling and linking problems.

*DBD. Beta*
     Now maintained by Jochen Wiedmann.  <<wiedmann@neckar-alb.de>>.
     Thanks!

*mysqlaccess. Beta*
     Written and maintained by <Yves.Carlier@rug.ac.be>. Thanks!

*The Technical Documentation. Beta*
     It is improving.

*MyODBC (uses ODBC SDK 2.5). Beta*
     It seems to work well with some programs.

   TcX provides email support for paying customers, but the *MySQL*
mailing list usually provides answers to all common questions. Bugs are
usually fixed right away with a patch that usually works and for
serious bugs there is almost always a new release.

Why are there is so many release of *MySQL*?
============================================

   Well, *MySQL* is evolving quite rapidly here at TcX and we want to
share this with other *MySQL* users. We try to make a release when we
have a very useful feature that others seem to have a need for.

   We also try to help out users who request features that are easy to
implement. We also take note on what our licensed users want to have and
we especially take notes of what our extended email supported customers
want and try to help them out.

   No one has to download a new release. The News section will tell you
if the new release has something you really want. *Note News::.

   If there is, by any chance, a fatal bug in a release we will make a
new release as soon as possible. We would like other companies to do
this too. :)

   The 3.21.x version incorporates major portability changes for many
different systems. When the 3.21 release is stable we will remove the
alpha/beta suffix and move active development to 3.22. Bugs will still
be fixed in the stable version. We don't believe in a complete freeze,
as this also leaves out bug fixes and things that 'must be done'.
'Somewhat freezed' means that we will maybe add small things that
'almost surely will not affect anything thats already working'.

   If you are running and old system and want to upgrade, but you don't
want to take chances with 3.21 you should upgrade to 3.20.32.  I have
tried to only fix fatal bugs and make small, relatively safe changes in
this version.

   If you are trying *MySQL* for the first time or have a little time
to test out that your current system, you should use 3.21.

Checking a table for errors
===========================

   If *MySQL* crashed (for example if the computer is turned off) when
all data is not written to disk the tables may have become corrupted. To
check a table use:

`isamchk table_name'
     This finds 99.99 % of all errors. What it can't find is when only
     the data file has been corrupted.

`isamchk -e table_name'
     This goes a complete and through check of all data. It does a
     check-read of all keys for every row to check that this indeed
     points to the right row.  This may take a LONG time on a big
     tables with many keys.  isamchk will normally stop after the first
     found error. If you want more information you can add the -verbose
     (-v) switch to isamchk.  In normal usage a simple 'isamchk' is
     safe enough!

`isamchk -e -i table_name'
     As the above but it also prints some statistics.

   We at TcX run a cron job on all our important tables once a week.

     35 0 * * 0 /path/to/isamchk -s /path/to/dbs/*/*.ISM

   This prints out any crashed tables so we can go and examine and
repair them when needed.

   As we haven't had any unexpected crashes (without hardware trouble)
tables for a couple of years now (this is really true), once a week is
more than enough for us.

   Of course, whenever the machine has done a reboot in the middle of a
update one usually has to check all the tables that could have been
affected. (This is an 'expected crashed table')

   We recommend that to start with, one should do a `isamchk -s' on all
updated tables each night until one comes to trust *MySQL* as much as
we do.

   Naturally, one could add a check to safe_mysql that, if there is an
old pid file left after a reboot, it should check all tables that have
been modified the last 24 hours.

How to repair tables
====================

   The file format that *MySQL* uses to store data has been extensively
tested, but there are always instances (like a hard kill on the mysqld
process in the middle of a write, a hardware error or a unexpected
shutdown of the computer) when some tables may be corrupted.

   The sign of a corrupted table is usually when queries abort
unexpectedly and one gets errors like:

   * table.frm is locked against change.

   * Can't find file 'table.ISM' (Errcode: ###)

   * Got error ### from table handler. (Error 135 is an exception in
     this case)

   * Unexpected end of file.

   * Record file is crashed.

   In these cases you have to repair your tables. The isamchk external
utility can usually detect and fix most things that go wrong. *Note
isamchk::.

   If you are going to use isamchk on very large files, you should first
decide how much memory you want to give to isamchk. More memory gives
more speed. For example, if you have more than 32M ram, try:

     isamchk -O sortbuffer=16M -O keybuffer=16M -O readbuffer=1M
             -O writebuffer=1M ....

   * Part 1: Checking
        * Check the permissions of the table files. Make them readable
          for the user running mysqld.

        * cd to the database directory.

        * Run 'isamchk *.ISM' or ('isamchk -e *.ISM' if you have more
          time).

        * You only have to repair those tables for which isamchk gives
          an error. Use option -s to avoid unnecessary information.

   * Part 2: Easy safe repair.
        * If you get weird errors when checking or repairing, such as
          out of memory errors or if isamchk crashes, go to part 3.

        * Try first 'isamchk -r -q table'. This will try to repair the
          .ISM file without touching the important data table (.ISD).
          If the data file (.ISD) contains everything and the delete
          links point at the right places in the data file, this should
          work and the table is fixed. Start repairing next table.

        * Make a backup of the data file (table.ISD) before continuing.

        * Use 'isamchk -r table'. This will remove wrong records and
          deleted records from the data file and reconstruct the index
          (.ISM) file.

        * If the above fails, use 'isamchk -safe-recover table'. This
          is a little slower than 'isamchk -recover table' but should
          work in all cases.

   * Part 3:; Hard repair.
        * This should only happen if the first 16K block in the .ISM
          file is destroyed, contains wrong information or if the .ISM
          is missing.

        * In this case we have to create a new .ISM file. Do as follows:

        * Move the data file .ISD file to some safe place.

        * Recreate the .ISM file from the .frm file:
               shell> mysql database
               mysql> delete from table_name;
               mysql> quit

        * Copy (don't move) the data file (.ISD) back on the newly
          created .ISD file

        * Go back to Part 2. (This shouldn't be a endless loop).
          isamchk -r -q should now work.

   * Part 4: Very hard repair.
          This can only happen if the descriptor file (.frm) also has
          crashed. This should never happen, because the .frm file
          isn't written after the table is created.

        * Restore the .frm file from a backup and go back to Part 3.
          You can also restore the .ISM file and go back to Part 2.  In
          the latter case you should start with 'isamchk -r'.

        * If you don't have a backup but know exactly how the table was
          created, create a copy of the table in another database and
          copy the .frm and .ISM file from there to your crashed
          database and go back to Part 2.

Is there anything special to do when upgrading/downgrading *MySQL*?
===================================================================

   One can always move the *MySQL* form and data files between
different versions on the same architecture as long as one has the same
base version of *MySQL*. The current base version is of course 3. If
one changes the character set (sort order) by recompiling *MySQL* one
has to do a `isamchk -r -q' on all tables.

   If you are paranoid and/or afraid of new versions you can always
rename your old mysqld to something like mysqld-'old-version-number'.
If your new mysqld then does something unexpected you can simple shut it
down and restart with your old mysqld!

   When you do a upgrade you should of course also take a backup of
your old databases.  Sometimes its good to be a little paranoid!

Upgrading to 3.22 from a 3.21 version
-------------------------------------

   Nothing that affects compatibility has changed.  The only pitfall is
that new tables that are created with a DATE type will use the new way
to store the date. This means that you can't access this field from an
old mysqld version.

   The C interface to mysql_real_connect() has changed.  If you have an
old client program that calls this, you must place a 0 for the new DB
argument (or recode the client to send the db element for faster
connections).

Upgrading to 3.21 from a 3.20 version
-------------------------------------

   If you already have a version older than 3.20.28 running and want to
switch to 3.21.# you need to do the following:

   You can start the `mysqld' 3.21 server with `safe_mysqld
--old-protocol' to use it with clients from the 3.20 distribution.  In
this case the new client function, `mysql_errno()', will not return any
server error, only `CR_UNKNOWN_ERROR', (but it works for client errors)
and the server uses the old password() checking instead of the new one.

   If you are *NOT* using `--old-protocol':

   * All client code must be recompiled. If you are using ODBC you must
     get the new myodbc 2.# driver

   * The script `scripts/add_long_password' must be run to convert the
     password field in the 'mysql/user' table to `char(16)'.

   * All passwords must be reassigned in the mysql/user table (to get
     62-bit instead of 31-bit passwords).

   * The table format hasn't changed so you don't have to convert any
     tables.

   *MySQL* 3.20.28 and above can handle the new user table format
without affecting clients. If you have a *MySQL* version below 3.20.28,
passwords will not work on it anymore if you convert the user table. So
to be safe, you should first upgrade to at least 3.20.28 and then
upgrade to 3.21.#.

   The new client code works with a 3.20.# mysqld server, so you can
use the old 3.20.# server if you experience problems with 3.21.#
without having to recompile the clients again.

   If you are not using the option `--old-protocol' to `mysqld', old
clients will issue the error message:

   `ERROR: Protocol mismatch. Server Version = 10 Client Version = 9'

   The new perl interface DBI/DBD also supports the old mysqlperl
interface.  The only change one has to do if one uses mysqlperl is to
change the arguments to the connect() function. The new arguments are:
host,database,user,password (the user & password arguments has changed
places).

   The following changes may effect queries in old applications.

   * `HAVING' must now be before any ORDER BY clause.

   * Parameters to `LOCATE()' has been swaped.

   * There are some new reserved words. Most notable are DATE, TIME and
     TIMESTAMP.

Upgrading to another architecture
---------------------------------

   Currently the *MySQL* data files *.ISM and *.ISD are architecture
dependent.  If you want to move your applications to another
architecture you should use mysqldump.

   mysqldump will (by default) create a file full of SQL statements
which you can then transfer to the other machine and then feed as input
to the mysqld server.

   Try `mysqldump --help' to check what options you can use.

   The easist way (not the fastest) way to move a database between two
connected machines are running this on the machine where the databases
are:

     mysqladmin -h 'other hostname' create database
     mysqldump --quick --drop database | mysql -h 'other hostname' database

   You can also store the result on file (compressed in this example):

     mysqldump --quick databasename | gzip > databasename.contents.gz
     
     # transfer the contents files to the target machine and use this
     # on the target machine
     
     mysqladmin create databasename
     gunzip < databasename.contents.gz | mysql databasename

   You can also use mysqldump and mysqlimport to do this: (This is much
faster than simply using mysqldump for big tables)

     mkdir full-path-to-some_dir
     mysqldump --tab=full-path-to-some-dir database
     
     # transfer the contents files to the target machine and use this
     # on the target machine
     
     mysqladmin create database
     cat full-path-to-some_dir/*.sql | mysql database
     mysqlimport database some_dir/*.txt

   Don't forget to also copy the 'mysql' database. You may have to use
the *MySQL* user "root" on the new machine until you've got the mysql
database in place.

   Finally (or straight after you import the 'mysql' database) do a :
`mysqladmin reload' on the new machine.

Year 2000 compliance
====================

   *MySQL* uses Unix times functions and has no problems with dates
until 2069; All 2 digit years are regarded to be in the range 1970-2069,
which means that if you store 01 in a `year' column, *MySQL* treats it
as 2001. In *MySQL* 3.22 the new `YEAR' column type can store years 0,
1901-2155 in 1 byte and display them with 2 or 4 digits.

   The year 2000 is only a problem for old applications that has stored
date with 2 digits and manipulates the date in many different programs
in with different functions.  All `MySQL' date functions are stored in
one file `sql/time.cc' and coded very carefully to be 2000 safe.

*MySQL* Server functions
************************

Which languages are supported by *MySQL*?
=========================================

   `mysqld' can give error messages in the following languages: Czech,
Dutch, English (default), French, German, Norwegian, Norwegian-ny,
Polish, Portuguese, Spanish and Swedish.

   To start `mysqld' with a language use one of the `--language=lang'
or `-L lang' switches:

   `mysqld --language=swedish' or `mysqld
--language=/usr/local/share/swedish'

   Note that all the language names are in lowercase.

   The language files are located (by default) in
`MYSQL_BASE_DIR/share/LANGUAGE/'.

   If you want to update the error message file, you should edit the
errmsg.txt file and execute `comp_err errmsg.txt errmsg.sys' to
generate the errmsg.sys file.

Character set used for data & sorting
-------------------------------------

   By default, *MySQL* will use the ISO8859-1 (Latin1) character set.
This is the character set used in the USA and western Europe.

   The character set decides what characters are allowed in names and
how things are sorted by the `ORDER BY' and `GROUP BY' commands.

   You may change this at compile time by the configure switch
`--with-charset=charset'. *Note Quick-install::.

   If you want to add another character set to *MySQL* you must:
   * Choose a name. CHARSET_NAME

   * Create the file
     `mysql_source_directory/strings/ctype-$CHARSET_NAME.c'.

   * Look at one of the existing ctype files to see what needs to be
     defined. Note that the arrays in this file must have names like
     ctype_$CHARSET_NAME, to_lower_$CHARSET_NAME and so on.

     tolower[] and toupper[] are simple arrays that holds the
     corresponding lower resp. upper character for each character.

     For example:
          to_lower['A'] should contain 'a'
          to_upper['a'] should contain 'A'

     sort_order[] is a map of how characters should be sorted. For many
     sets this is the same as to_upper (case insensitive sorts).
     *MySQL* will sort characters based on the value of
     sort_order[character].

     ctype[] is a array of bits that describes each character. Note
     that ctype[] does have a offset of 1 (old legacy to be able to
     handle EOF) You can find the following definitions in m_ctype.h:

          #define _U      01      /* Upper case */
          #define _L      02      /* Lower case */
          #define _N      04      /* Numeral (digit) */
          #define _S      010     /* Spacing character */
          #define _P      020     /* Punctuation */
          #define _C      040     /* Control character */
          #define _B      0100    /* Blank */
          #define _X      0200    /* heXadecimal digit */

     For example ctype['A'+1] should contain the value:

     `_U + _X = 0201'

   * Add to include/m_ctype.h.in a unique number for the char set.

   * Add charset name to `CHARSETS_AVAILABLE' list in `configure'.in

   * Recompile and test

   *  If you are making a multiple-character char set, you can use the
_MB macros.  In `strings/m_ctype.h.in' add:

     #define MY_CHARSET_<C>		X
     #if MY_CHARSET_CURRENT == MY_CHARSET_<C>
     #define USE_MB
     #define USE_MB_IDENT
     #define ismbchar(p, end)	(...)
     #define ismbhead(c)		(...)
     #define mbcharlen(c)		(...)
     #define MBMAXLEN		N
     #endif

MY_CHARSET_<C>         unique value.                                      
USE_MB                 This charset have mb-char.                         
USE_MB_IDENT:          Use mb-char as identifier. (optional)              
ismbchar(p, e)         return 0 if not mb-char, or size of char if        
                       mb-char.  Check from (char*)p to (char*)e-1.       
ismbhead(c)            Is c first char of mb or not?                      
mbcharlen(c)           Size of char if c is first char of mb.             
MBMAXLEN               Maximum size of one character.                     

The Update log
==============

   When started with the `--log-update=file_name' switch `mysqld' makes
a log file with all SQL command that update data. It results in a file
with name of `file_name.#' where # is a number that is increased for
each refresh. If you do not give a file name the current hostname is
used.

   The logging is smart since it only writes statements that really
update data. So an `UPDATE' or a `DELETE' with a `WHERE' that finds no
rows is not written to the log. It even skips `UPDATE's that updates a
column to the value it had before.

   If you want to update a database according from a update log you
could do the following:
     cat file-name.* | mysql

How big can *MySQL* tables be?
==============================

   Currently a table is limited to the operation system file size.  On
Linux the current limit is 2G, on Solaris 2.5.1 the limit is 4G and on
Solaris 2.6 the limit is going to be 1000G. To get more that 4G requires
some changes to *MySQL* that are on the Todo. *Note Todo::.

   If your big table is going to be read_only, you could use pack_isam
(*Note pack_isam::) to merge and compress many tables to one.  As
pack_isam usually compresses a table by at least 50%, you can have much
bigger tables.

   Another solution can be the included MERGE library, which allows one
to handle a collection of identical tables as one. Currently MERGE can
only be used to scan a collection of tables because it doesn't support
indexes. We will add indexes to this in the near future.  Identical in
this case means that all tables are created with identical column
information.

How to get maximum performance out of *MySQL*
*********************************************

How does one change the size of *MySQL* buffers?
================================================

   You can get the current buffer sizes with:

   > `./mysqld --help'

   This should result in a list of all mysqld options and configurable
variables like the following.

     Possibly variables to option --set-variable (-O) are:
     back_log              current value: 5
     join_buffer           current value: 131072
     key_buffer            current value: 1048568
     max_allowed_packet    current value: 65536
     max_connections       current value: 90
     max_join_size         current value: 4294967295
     max_sort_length       current value: 1024
     net_buffer_length     current value: 8192
     record_buffer         current value: 131072
     sort_buffer           current value: 2097144
     table_cache           current value: 64
     tmp_table_size        current value: 1048576
     thread_stack          current value: 65536

back_log                How many outstanding connection requests may      
                       *MySQL* have. This comes into play when the main   
                       *MySQL* thread gets *VERY* many connection         
                       requests in a very short time. It then takes some  
                       time (but very short) for the main thread to       
                       check the connection and start a new thread. The   
                       back_log is how many connects can be stacked       
                       during this short time before *MySQL* momentarily  
                       stops answering new requests. You only need to     
                       increase this if you expect a large number of      
                       connections in a short period of time.             
                                                                          
                          In other words, the size of the listen queue    
                       for incoming tcp/ip connections.  The manual page  
                       for the unix system call listen(2) should have     
                       more details.                                      
                                                                          
                          Check your OS documentation for the maximum     
                       value for this variable.                           
join_buffer             This buffer is used for full joins (without       
                       indexes). It is allocated one time for each full   
                       join between two tables. Increase this to get a    
                       faster full join when adding indexes is not        
                       possible. Normally the best way to get fast joins  
                       is by adding indexes.                              
key_buffer              Buffers index blocks and are shared by all        
                       threads. You might want to increase this when      
                       doing many delete/inserts on a table with lots of  
                       indexes. To get even more speed use `LOCK          
                       TABLES'. *Note Lock tables::.                      
max_allowed_packet      Max size of one packet. This allows the message   
                       buffer to grow up to this limit when needed (it    
                       is initiated to `net_buffer_length'). May be set   
                       very big because this is mainly to find erroneous  
                       packets. You must increase this if you are using   
                       big BLOBS. It should be as big as the biggest      
                       BLOB you want to use.                              
max_connections         How many simultaneous clients are allowed. If     
                       you increase this you probably has to increase     
                       the number of file descriptors mysqld has. This    
                       is Operating system depended so look at you OS     
                       documentation.                                     
max_join_size           Joins that touch more records than max_join_size  
                       return an error. Set this if you have users to     
                       tend to make joins without a `WHERE' that take a   
                       long time and return millions of rows.             
max_sort_length         The number of bytes to use when sorting on        
                       `BLOB' or `TEXT' columns.                          
net_buffer_length       The communication buffer is reset to this size    
                       between queries. This should not normally be       
                       changed, but if you have very little memory you    
                       can set it to the expected size of a query.        
record_buffer           Each thread that is doing a sequential scan       
                       allocates a buffer of this size for each table it  
                       scans. If you do many sequential scans you may     
                       want to increase this.                             
sort_buffer             Each thread that needs to do a sort allocates a   
                       buffer of this size. Increase this for faster      
                       `ORDER BY' or `GROUP BY'.  *Note Temporary files:: 
table_cache             Number of open tables for all threads. If this    
                       is increased you must see to that the number of    
                       open file descriptor is also increased. *MySQL*    
                       needs two file descriptors for each unique table.  
tmp_table_size          If a temporary table gets bigger than this a      
                       `The table ### is full' error will be generated.   
                       Increase this if you do many advanced `GROUP BY'   
                       queries.                                           
thread_stack            How big will each threads `C' stack be. A lot of  
                       the limits detected by crash-me are dependent on   
                       this. The default is normally enough.              

   *MySQL* uses algorithms that are very scalable so one can usually
run with very little memory or give *MySQL* more memory to get better
performance.

   If you have much memory and many tables and want maximum performance
with a moderate number of clients you should use something like:
     > safe_mysqld -O key_buffer=16M -O table_cache=128 \
             -O sort_buffer=4M -O record_buffer=1M &

   If you have little memory with lots of connections, use something
like:
     > safe_mysqld -O key_buffer=512k -O sort_buffer=100k -O record_buffer=100k &

   or even

     > safe_mysqld -O key_buffer=512k -O sort_buffer=16k -O table_cache=32 \
             -O record_buffer=8k -O net_buffer=1K &

   Note that if you change an option to `mysqld' it is only for that
instance of the server. To see the effects of a parameter change, do
something like this `mysqld -O key_buffer=32m --help'.  You can check
the parameters in effect with `mysqladmin variables'.

   If there are very many connections, 'swapping problems' may occur if
mysqld has not been configured to use very little memory for each
connection. It also works better if you have a enough memory for all
connections of course.

   For example, for 200 open connections one should have a table cache
of at least 200 * (max_number of tables in join).

How compiling and linking affects the speed of *MySQL*
======================================================

   Most of the following test are done on Linux and with the *MySQL*
benchmarks, but they should give some indication for other operating
systems:

   On Linux you will get the fastest code when compiling with pgcc and
-O6.  To compile sql_yacc.cc with these options one needs 180M memory as
gcc/pgcc needs a lot of memory to make all functions inline.  One
should also set CXX=gcc when configuring *MySQL* to avoid inclusion of
the libstdc++ library.

   One gets the fastest executable when one links with -static. Using
Unix socket instead of TCP/IP to connect to a database gives also better
performance.

   bullet If you use pgcc instead of gcc and compile everything with -O6
     the program will be 11 % faster than with gcc.

   bullet If you link dynamically (without -static), the result is 13 %
     slower.

   bullet If you use TCP/IP instead of Unix sockets (connection to
     localhost), the result is 7.5 % slower.

   bullet On a Sun sparcstation 10 gcc 2.7.3 is 13 % faster than Sun
     Pro C++ 4.2.

   bullet On Solaris 2.5.1, MIT-pthreads is 8-12% slower than Solaris
     native threads.

   The *MySQL*-linux distribution that is distributed by TCX is
compiled with pgcc and linked statically.

How does *MySQL* use memory?
============================

   * The key_buffer is shared by all threads, the rest are allocated
     when needed.

   * Each connection uses some thread space, a stack (64K) and a
     connection buffer (variable `net_buffer_length').

   * All threads share the same base memory.

   * Nothing is memmapped yet (except compressed tables but that's
     another story). This is because the 32-bit memory space of 4GB is
     not large enough for most large tables. When we get a system with
     64-bit address space we may add general support for memmaping.

   * When starting `mysqld' one can specify a key buffer. This will
     buffer all indexes in all tables on a FIFO basis (variable
     key_buffer).

   * Each request doing a sequential scan over a table allocates a read
     buffer (variable record_buffer).

   * Most requests doing a sort allocates a sortbuffer and one or two
     temporary files. *Note Temporary files::

   * All joins are done in one pass and most joins can be done without
     even using a temporary table. Most temporary tables are memory
     based (HEAP) tables. Temporary tables with a big recordlength (=
     sum of all column lengths) or that contains `BLOB's are stored on
     disk.  One current problem is that if the HEAP table exceeds the
     size of `tmp_table_size', one will get the error: 'The table ###
     is full'.  In the future we will fix this by automatically
     changing the in memory (HEAP) table to a disk based (NISAM) table
     if needed.  To go around this problem one can increase the `-O
     tmp_table_size=#' option to mysqld or use the SQL option
     `SQL_BIG_TABLES'.  *Note Set option::.  In *MySQL* `3.20' the
     maximum size of the temporary table was `recordbuffer*16', so if
     you are using this version you have to increase `recordbuffer'.
     You can also start mysqld with -big-tables to always store
     temporary tables on disk, but this will affect the speed of all
     complicated queries.

   * Almost all memory used when parsing and calculating is done in a
     local memory store. No memory overhead is needed for small items
     and the normal slow memory allocation/freeing is avoided. Memory
     is only allocated for unexpectedly large strings (this is done
     with malloc/free).

   * Each index file is opened once and the data file is opened once
     for each concurrently-running thread. For each concurrent thread a
     table structure, column structures for each column, and a buffer
     that has the size of 3 * (maximum row length not counting `BLOB's)
     is allocated. A `BLOB' uses 5 to 8 bytes +length of blob data.

   * For each table having `BLOB's, a buffer is enlarged dynamically to
     read in larger `BLOB's. If one scans a table there will be a
     allocated buffer as large as the largest `BLOB'.

   * All used tables are saved in a cache and managed as a FIFO.
     Normally the cache is 64 tables. If a table has been used by two
     running threads at the same time, there will be two entries of the
     table in the cache.

   * A `mysqladmin refresh' closes all tables that are not in use and
     marks all used tables to be closed when the running thread
     finishes. This will effectively free most used memory. All log
     files are also closed and reopened.

   When running *mysqld* `ps' and other programs may report that it
uses a lot of memory. This may be caused by thread-stacks on different
memory addresses. For example, the Solaris ps calculates the unused
memory between stacks as used memory. You can verify this by checking
available swap with 'swap -s'. We have tested `mysqld' with commercial
memory-leakage detectors so there should not be any memory leaks.

How does *MySQL* use indexes?
=============================

   All indexes, `PRIMARY', `UNIQUE' and `INDEX()', are stored in B
trees. Strings are automatically prefix- and end-space compressed.
*Note Create Index::

What kind of optimisation is done on the WHERE clause?
======================================================

   (Incomplete, *MySQL* does a lot of optimisations.)

   The first issue about making a slow `SELECT ... WHERE' faster is to
check if one could add an index. All references between different
tables should usually be done with indexes. One can use the `EXPLAIN'
command to check which indexes are used in a `select'. *Note Explain::.
*Note MySQL indexes::

   * Brace removal (all unnecessary braces are removed). `((a AND b)
     AND c OR (((a AND b) AND (c AND d))))' -> `(a AND b) OR (a AND b
     AND c AND d)'

   * Constant folding. `(a<b AND b=c) AND a=5' -> `b>5 AND b=c AND a=5'

   * Constant condition removal (needed because of constant folding).
     `(b>=5 AND b=5) OR (b=6 AND 5=5) OR (B=7 AND 5=6)' -> `B=5 OR B=6'

   * All constant expressions used by indexes are evaluated only once.

   * `CONST(*)' on a single table without a `WHERE' is retrieved
     directly from the table.  This is also done for any `NOT NULL'
     expression under the same conditions.

   * Early detection of invalid constant expressions. Return zero rows
     if impossible select.

   * `HAVING' is merged with `WHERE' if one doesn't use `GROUP BY' or
     group functions.

   * For each sub join a simpler `WHERE' is constructed to get a fast
     `WHERE' evaluation for each sub join and also to skip records as
     soon as possible.

   * Find all indexes that may be used. Use the index which finds least
     records. An index is used for the following cases: `=', `>', `>=',
     `<', `<=', `BETWEEN' and a `LIKE' with a character prefix like
     'something%'.

   * Remove indexes that don't span all `AND' levels.
        - have all preceding index_parts specified.

        - `index = 1 or A = 10' -> `NULL' (can't use index.)

        - `index = 1 or A = 10 and index=2' -> `index = 1 OR index = 2'

        - `index_part_1 = const and index_part_3 = const' ->
          `index_part_1 = const'

   * Read all constant tables. A constant table is:

       1. A table with 0 or 1 record.

       2. A table which uses only other const tables and constants on a
          full unique index.

          `const_table.index = constant'

        * `const_table.index_part_1 = const_table2.column and
          const_table.index_part_2 = constant'

   * Find the best join combination to join the tables, by trying all
     possibilities :(. If all columns in `ORDER BY' and in `GROUP' come
     from the same table, then this table is preferred first when
     joining.

   * If there is an order clause and a different group clause, or if
     the order or group contains columns from other tables than the
     first table in the join queue, a temporary table is created.

   * For each table use a ranged index, if possible, to read records.
     Each table index is queried and if there is an index range that
     spans < 30% of the records then an index is used. If no such index
     can be found a quick table scan is used.

   * Before each record is output, skip those that match the `HAVING'
     clause.

How does *MySQL* open & close tables?
=====================================

   The cache of open tables can grow to a maximum of `table-cache'
(default 64, changeable with -O table_cache=#).  A table is never
closed, except when the cache is full and another thread tries to open
a table or if one uses 'mysqladmin refresh'.

   When the limit is reached, *MySQL* closes as many tables as
possible, until the cache size has been reached or there are no more
unused tables.  This means that if all tables are in use by some
threads, there will be more open tables than the cache limit, but the
extra tables will be closed eventually.  Tables are closed according to
last-used order.

   A table is opened (again) for each concurrent access. This means that
if one has two threads running on the same table or access the table
twice in the same query (with `AS') the table needs to be opened twice.
The first open of any table takes two file descriptors, each following
use of the table takes only one file descriptor.

   You can move tables and databases from the database directory to
other disks and put a symbolic links instead of the old
files/directories.

   If *MySQL* notices that a table is a symbolic linked it will resolve
the symlink and use the table it points to instead. This works on all
system that supports the realpath() call (At least Linux and Solaris
supports realpath())!  On system that doesn't supports realpath() you
should not use the symlink and the table at the same time!  The tables
will be inconsistent after any update to the tables.

   *MySQL* doesn't support linking of databases by default.  Things
will work fine as long as you don't make a symbolic link between
databases.  The following shows a case that *DOES NOT* work:

     db2->db1
     db1/

   If you really need this you have to change in mysys/mf_format.c:

         if (!lstat(to,&stat_buff))		/* Check if it's a symbolic link */
           if (S_ISLNK(stat_buff.st_mode) && realpath(to,buff))
     
     to
           if (realpath(to,buff))

What are the drawbacks of creating possibly thousands of tables in a database?
..............................................................................

   Each table is actually three files.  If you have many files in a
directory open, close and create will be slow.  If you also do selects
on many different tables there will be a little overhead because when
the table cache is full, for every table that has to be opened another
has to be closed. One can make the overhead smaller by making the table
cache larger.

How does *MySQL* lock tables?
=============================

   All locking in *MySQL* is deadlock free.  This is managed by always
requesting all needed locks at once at query start and always locking
the tables in the same order.

   The locking method *MySQL* uses for `WRITE' lock works as follows:

   If there is no locks on the table, put a write lock on it, else put
the lock in the write lock queue.

   The locking method *MySQL* uses for `READ' locks works as follows:

   If there is no write locks on the table, put a read lock on it else
put the lock in the read lock queue.

   When a lock is released first use give the lock to the threads in
the write lock queue and after this to the threads in the read lock
queue.

   This means that if you have many updates on the same table, select
statements will be waiting until there is no more updates.

   To fix this in the case where you do many inserts and many selects
on the same table you could insert rows in another table and once in a
while update the other table with all records from the temporary table.

   This can be done with the following code:
     LOCK TABLES real_table WRITE, insert_table WRITE
     insert into real_table select * from insert_table
     delete from insert_table
     UNLOCK TABLES

   One could also change the locking code in mysys/thr_lock.c to use
only one queue.  In this case write locks would have the same priority
that read locks and this could help some applications.

How should I arrange my table to be as fast/small as possible?
==============================================================

   * Use `NOT NULL' if possible. It makes everything faster and you
     save one bit per column.

   * All columns have default values. Only insert when the default value
     isn't acceptable. You don't have to insert the columns of a
     timestamp or an autoincremented index in the insert statement.
     *Note mysql_insert_id::.

   * Use the smaller INT types if possible to get smaller tables. For
     example, `MEDIUMINT' is often better than `INT'.

   * If you don't have any `VARCHAR' columns, a fixed size record format
     will be used. This is much faster but may unfortunately waste some
     space. *Note Row format::.

   * To make *MySQL* optimize queries better, run `isamchk --analyze'
     on the table once it is loaded with relevant data. This updates a
     value for each index that tells how many rows that have the same
     value for this index on average. Of course, this is always 1 for
     unique indexes.

   * To sort an index and data according to an index use `isamchk
     --sort-index --sort-records=1' (if you want to sort on index 1).
     If you have a unique index from which you want to read all records
     in numeric order, this is a good way to make that faster.

   * When loading a table with data use `LOAD DATA FROM INFILE'. This is
     usually 20 times faster than using a lot of `INSERT's. If the text
     file isn't on the server, rcp it to the server first. *Note Load::.

     You can even get more speed when loading data to tables with many
     indexes by doing:
        * Create the table in mysql or perl with `CREATE TABLE...'

        * Do `mysqladmin refresh'.

        * Use `isamchk --keys-used=0 database/table_name'. This will
          remove all usage of all indexes from the table.

        * Insert data into the table with `LOAD DATA INFILE...'.

        * If you have pack_isam and want to compress the table, run
          pack_isam on it.

        * Recreate the indexes with `isamchk -r -q database/table_name'.

        * Do `mysqladmin refresh'.

     The other possibility to get some more speed for both `LOAD DATA
     FROM INFILE' and `INSERT' is to enlarge the key buffer.  This can
     be done with the `-O key_buffer=#' option to `(safe)mysqld'.  For
     example 16M should be a good value if you have much RAM :)

   * When dumping data as textfiles to other programs, use `SELECT ...
     INTO OUTFILE'. *Note Load::.

   * When doing many inserts/updates in a row, you can get more speed
     by using `LOCK TABLES' on the tables. `...FROM INFILE...' and
     `...INTO OUTFILE...' are atomic so you don't have to use `LOCK
     TABLES' when using these. *Note Lock tables::.

   To check how you are doing, run `isamchk -evi' on the .ISM file.

What affects the speed of the INSERT statement?
===============================================

   The time to insert a record consists of:

   * Connect:                 (3)

   * Sending query to server: (2)

   * Parsing query:           (2)

   * Inserting record:        (1 x size of record)

   * Inserting indexes:       (1 x indexes)

   * Close:                   (1)

   Where (number) is proportional time. This does not take into
consideration the initial overhead to open tables (which is done once
for each simultaneous running query).

   The size of the table slows down the insert of indexes by N log N
(B-trees).

   A way of speeding up inserts is to lock your table during the
inserts.

     LOCK TABLES a WRITE;
     
     INSERT INTO a VALUES (1,23)
     INSERT INTO a VALUES (2,34)
     INSERT INTO a VALUES (4,33)
     INSERT INTO a VALUES (8,26)
     INSERT INTO a VALUES (6,29)
     
     UNLOCK TABLES;

   The main speed difference is that the index buffer is only flushed
once to disk for all inserts. Normally there would be as many index
buffer flushes as there are inserts.

   Locking will also lower the total time of multi-connection test but
the maximum wait time for some threads will go up.

   For example:

     thread 1 does 1000 inserts
     thread 2, 3, and 4 does 1 insert
     thread 5 does 1000 inserts

   If you don't use locking, 2, 3 and 4 will finish before 1 and 5. If
you use locking 2,3,4 may finish before 1 or 5 but probably not, but the
total time should be about 40% faster.

   As `INSERT's, `UPDATE's and `DELETE's are very fast in *MySQL*, one
will obtain better overall performance by adding locks around
everything that does more than about 5 inserts/updates in a row.  If
one does very many inserts in a row one could do a `UNLOCK TABLES'
followed by a `LOCK TABLES' once in a while (about each 1000 rows) to
give other threads access to the table. This would still give a nice
performance gain.

   Of course `LOAD DATA INFILE' is much faster still.

What affects the speed of DELETE statement?
===========================================

   The delete time of a record is exactly proportional to the number of
indexes. To increase the speed of deletes you can increase the size of
the index cache. The default index cache is 1M and to get faster
deletes it should be increased by several factors (try 16M if you have
enough memory).

How do I get *MySQL* to run at full speed?
==========================================

   Start with benchmarking your problem!  You can take any of the
programs from the *MySQL* benchmark suite (normally found in the
`sql-bench' directory) and modify it for your needs.  By doing this you
can try different solutions to your problem and test which is really
fastest solution for you.

   * Start `mysqld' with the right options. More memory gives more speed
     if you have it. *Note MySQL parameters::.

   * Create indexes to make your `SELECT's faster. *Note MySQL indexes::

   * Optimize your column types to be as efficient as possible. Use
     `NOT NULL' on all columns.  *Note Table efficiency::

   * `--skip-locking' disables file locking between SQL requests. This
     gives a greater speed but has the following consequences:
        * One *MUST* flush all tables with `mysqladmin refresh' before
          one tries to check/repair tables with `isamchk'. (`isamchk -d
          table_name' is always allowed).

        * One can't run two *MySQL* servers one the same data files, if
          both are going to update the same tables.  The
     `--skip-locking' is on by default when compiling with MIT-pthreads.
     This is because flock() isn't fully supported by MIT-pthreads on
     all platforms.

   * If updates are a problem, one can delay updates and then do many
     updates in a row later. Many updates done in a row are much
     quicker than one at a time.

   * If the problem is with MIT-pthreads and one is using FreeBSD,
     upgrading to FreeBSD 3.0 (or higher) should help. This gives a
     possibility to use sockets (quicker than the current TCP/IP with
     MIT-pthreads) and the thread package is much more integrated.

What are the different row formats? Or when to use VARCHAR/CHAR?
================================================================

   *MySQL* dosen't have true SQL VARCHAR() types.

   *MySQL* has instead 3 different ways to store records and uses this
to emulate `VARCHAR()':

   If one doesn't use any of the `VARCHAR', `BLOB' or `TEXT' column
types a fixed row size is used, otherwise a dynamic row size is used.
`CHAR()' and `VARCHAR()' are treated identically from the applications
point of view; Both truncates end space from the column when the column
is accessed.

   You can check the format used in a table with `isamchk -d'.

   *MySQL* has three different table formats:

  1. Fixed length tables.
        * This is the default format. It's used when there is no
          VARCHAR(), TEXT or BLOB column types in the table.

        * All CHAR(), NUMERIC() and DECIMAL() columns are space filled.

        * Very quick.

        * Easy to cache.

        * Easy to reconstruct after a crash as records are in fixed
          positions.

        * Don't have to be reorganised (with isamchk) unless a huge
          number of records are deleted and one wants to free space to
          the operating system.

        * This will usually take more disk space than dynamic tables.

  2. Dynamic tables
        * Is used if there exists any columns with a `VARCHAR', `TEXT'
          or `BLOB' type in a table.

        * All strings are dynamic (except if length < 3).

        * Each record is preceded with a bitmap for which columns are
          empty (") or zero (this isn't the same as null columns). Each
          string is saved with a length byte + string. If string is
          zero length or is number zero it is marked in the bit map and
          not saved to disk.

        * Each record is uses the exact record space required. If a
          record becomes larger it is split into as many pieces as
          required.

        * Takes usually much less disk space than fixed length records.

        * If one updates rows with information that extends the row
          length the row will be fragmented.  In this case one may have
          to run `isamchk -r' from time to time to get better
          performance.  Use `isamchk -ei table_name' for some
          statistics.

        * Not as easy to reconstruct because a record may be in many
          pieces and a link may be missing.

        * The expected row length for dynamic sized records is: 3 +
          (number_of_columns + 7) / 8 + (number of char columns) +
          packed_size_of_number_columns + length_of_strings +
          (null_columns + 7) / 8. There will be a penalty of 6 bytes
          for each link. A dynamic record will be linked whenever an
          update causes an enlargement of the record. Each new link
          will be at least 20 bytes, so the next enlargement will
          probably go in the same link. If not, there will be another
          link. You may check how many links there are with `isamchk
          -ed'. All links may be removed with `isamchk -r'.

  3. Compressed tables:
        * A read only table made with the pack_isam utility. All
          customers with extended *MySQL* email support are entitled to
          a copy of pack_isam for their intern usage.

        * The uncompress code exists in all *MySQL* distributions so
          even customers that doesn't have pack_isam can read tables
          compressed with pack_isam (on the same platform).

        * Takes very little disk space. Minimises disk usage.

        * Each record is compressed separately (very little access
          overhead).  The header for a record is fixed 1-3 bytes
          depending on the biggest record in the table.  Each column is
          compressed differently. Some of the compression types are:
             * There is usually a different Huffman table for each
               column.

             * Suffix space compression.

             * Prefix space compression.

             * Numbers with value 0 is stored with 1 bit.

             * If a integer is used with a smaller range the integer
               column is stored with the smallest possibly type. For
               example a LONGLONG (8 bytes) column may be stored as
               TINYINT column if all values are in the range 0-255.

             * If a value has only a small set of possible values, the
               value is converted to enum().

             * A column may use a combination of the above compressions.

        * Can handle fixed or dynamic length records, but no BLOB or
          TEXT columns.

        * Can be uncompressed with isamchk.

   *MySQL* can support different index types, but the normal one is
NISAM.  This is a B-tree index and one can roughly calculate the size
for the index file as: sum over all keys:

   `(key_length+4)*0.67'

   (This is for the worst case when all keys are inserted in sorted
order.

   String index are space compressed and if the first index part is a
string it will also be prefix compressed.  This will usually make the
index file smaller if the columns are not filled up to 100% or if there
are many duplicates.

Why so many open tables?
========================

   When you run `mysqladmin status' you get something like:

     Uptime: 426 Running threads: 1 Questions: 11082 Reloads: 1 Open tables: 12

   This can be somewhat perplexing if you only have 6 tables.

   As *MySQL* is multithreaded it may have many queries on the same
table at once. To minimise the problem with two threads having
different states on the same file, I open the table again for each
concurrent thread. This takes some memory and one extra file descriptor
for the data file. The index file descriptor is shared between all
threads.

*MySQL* benchmark suite
***********************

   This should contain a technical description of the *MySQL* benchmark
suite (and crash-me) but that description is not written yet. Currently
see the code and results in the `bench' directory in the distribution.
And of course on the web page (http://www.tcx.se/crash-me.html).

   It is meant to be a benchmark that will tell any user what things a
given SQL implementation is good or bad at.

   crash-me tries to find what a database supports by actually running
queries. It find for example:

   * What column types are supported.

   * How many indexes.

   * What functions are supported.

   * How big can a query be.

   * How big can a varchar column be.

*MySQL* Utilites
****************

Overview of the different *MySQL* programs
==========================================

   All *MySQL* clients that communicate with the server using the
`mysqlclient' library use the following environment variables:

Name                   Description                                        
MYSQL_UNIX_PORT        The default socket. Used with 'localhost'.         
MYSQL_TCP_PORT         The default TCP port.                              
MYSQL_PWD              The default password.                              
MYSQL_DEBUG            Debug-trace options when debugging.                
TMPDIR                 Directory where temporary tables/files are         
                       created.                                           

   All *MySQL* programs take many different options. Use the switch
-help to get a full description of the different options. Try for
example `mysql --help'.

`mysql'
     mysql is a simple SQL shell (with GNU readline). It supports
     interactive use and non-interactive querying. When used
     interactively, the result are given in an ascii-table format, but
     when used as a filter the result is a tab-separated output (this
     as other things can be changed with startup options).  You can
     simply run scripts with `mysql database < script.sql > output.tab'.
     If you have a problem with that the memory in the client is not
     enough, use the `--quick' switch!  This will force mysql to use
     `mysql_use_result()' instead of `mysql_store_result()' to retrieve
     the result set.

`mysqlaccess'
     Script to check the privileges for a host, user and database
     combination.

`mysqladmin'
     Administration utility. Create/Drop databases, reload (read new
     users) and refresh (flush tables to disk, reopen log files). Also
     gives version, process and status information from the server.

`mysqld'
     The SQL daemon. This should always be running.

`mysqldump'
     Dump a *MySQL* database into a file with SQL statements or tab
     separated text files. Enhanced freeware originally by Igor
     Romanenko.

`mysqlimport'
     Imports one or more text files into respective tables. Can use all
     formats supported by `LOAD DATA INFILE'. *Note Load::

`mysqlshow'
     Shows information about databases, tables, columns and indexes.

`mysqlbug'
     This script should always be used when filing a bug report to the
     *MySQL* list.

`mysql_install_db'
     Creates the *MySQL* grant tables with default privileges. This is
     usually only executed once when installing the first *MySQL*
     release on a new system.

`isamchk'
     Check, optimise and repair *MySQL* tables.

`make_binary_release'
     Makes a binary release of a compiled *MySQL*. This could be sent
     by ftp to /pub/mysql/Incoming on www.tcx.se for the convenience of
     other *MySQL* users.

`msql2mysql'
     A shell script to convert a `mSQL' program to *MySQL*. Doesn't
     handle all cases but gives a good start when converting.

`replace'
     Binary used for msql2mysql. Utility program to change strings in
     place in files or on stdin. Uses a finite state machine to match
     longer strings first. Can be used to swap strings, for example
     `replace a b b a -- files' swaps `a' and `b' in the given files.

`safe_mysqld'
     Starts the mysqld daemon with some safety features. Restarts on
     error and has logging of runtime information to a log file.

The *MySQL* table check, optimise and repair program
====================================================

   You can get all options for isamchk with `isamchk --help'.

   For information about how to use isamchk to repair a crashed table:
*Note Repair::.

isamchk memory use
------------------

   `isamchk' doesn't use any more memory than you define with the `-O'
options. The default is to use only about 3M to fix things.  By using
bigger values you can get isamchk to operate faster.  Using `-O
sortbuffer=16M' should probably be enough for most cases.

   But `isamchk' uses temporary files in `TMPDIR'. If `TMPDIR' points
to a memory file system you may easily get out of memory errors.

Getting low level table information
-----------------------------------

   To get a description/statistics from a table use the methods below.
We will explain some of the information in more detail later.

`isamchk -d table_name'
     isamchk in 'describe mode'. If one uses `--skip-locking' `isamchk'
     may report an error for a table that is updated while isamchk
     runs, but there isn't any risk of destroying data.

`isamchk -d -v table_name'
     A little more verbose.

`isamchk -eis table_name'
     Shows only the most important information from a table. It is slow
     since it must read the whole table.

`isamchk -eiv table_name'
     Same as above but tells you what it is being done.

   Example of `isamchk -d' output:
     ISAM file:     company.ISM
     Data records:           1403698  Deleted blocks:         0
     Recordlength:               226
     Record format: Fixed length
     
     table description:
     Key Start Len Index   Type
     1   2     8   unique  double
     2   15    10  multip. text packed stripped
     3   219   8   multip. double
     4   63    10  multip. text packed stripped
     5   167   2   multip. unsigned short
     6   177   4   multip. unsigned long
     7   155   4   multip. text
     8   138   4   multip. unsigned long
     9   177   4   multip. unsigned long
         193   1           text

   Example of `isamchk -d -v' output:
     ISAM file:     company.ISM
     Isam-version:  2
     Creation time: 1996-08-28 11:44:22
     Recover time:  1997-01-12 18:35:29
     Data records:           1403698  Deleted blocks:              0
     Datafile: Parts:        1403698  Deleted data:                0
     Datafilepointer (bytes):      3  Keyfile pointer (bytes):     3
     Max datafile length: 3791650815  Max keyfile length: 4294967294
     Recordlength:               226
     Record format: Fixed length
     r
     table description:
     Key Start Len Index   Type                      Root Blocksize Rec/key
     1   2     8   unique  double                15845376      1024       1
     2   15    10  multip. text packed stripped  25062400      1024       2
     3   219   8   multip. double                40907776      1024      73
     4   63    10  multip. text packed stripped  48097280      1024       5
     5   167   2   multip. unsigned short        55200768      1024    4840
     6   177   4   multip. unsigned long         65145856      1024    1346
     7   155   4   multip. text                  75090944      1024    4995
     8   138   4   multip. unsigned long         85036032      1024      87
     9   177   4   multip. unsigned long         96481280      1024     178
         193   1           text

   Example of `isamchk -eis' output:
     Checking ISAM file: company.ISM
     Key:  1:  Keyblocks used:  97%  Packed:    0%  Max levels:  4
     Key:  2:  Keyblocks used:  98%  Packed:   50%  Max levels:  4
     Key:  3:  Keyblocks used:  97%  Packed:    0%  Max levels:  4
     Key:  4:  Keyblocks used:  99%  Packed:   60%  Max levels:  3
     Key:  5:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     Key:  6:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     Key:  7:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     Key:  8:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     Key:  9:  Keyblocks used:  98%  Packed:    0%  Max levels:  4
     Total:    Keyblocks used:  98%  Packed:   17%
     
     Records:          1403698    M.recordlength:     226   Packed:             0%
     Recordspace used:     100%   Empty space:          0%  Blocks/Record:   1.00
     Recordblocks:     1403698    Deleteblocks:         0
     Recorddata:     317235748    Deleted data:         0
     Lost space:             0    Linkdata:             0
     
     User time 1626.51, System time 232.36
     Maximum resident set size 0, Integral resident set size 0
     Non physical pagefaults 0, Physical pagefaults 627, Swaps 0
     Blocks in 0 out 0, Messages in 0 out 0, Signals 0
     Voluntary contexts switches 639, Involuntary contexts switches 28966

   Example of `isamchk -eiv' output:
     Checking ISAM file: company.ISM
     Data records: 1403698   Deleted blocks:       0
     - check file-size
     - check delete-chain
     index  1:
     index  2:
     index  3:
     index  4:
     index  5:
     index  6:
     index  7:
     index  8:
     index  9:
     No recordlinks
     - check index reference
     - check data record references index: 1
     Key:  1:  Keyblocks used:  97%  Packed:    0%  Max levels:  4
     - check data record references index: 2
     Key:  2:  Keyblocks used:  98%  Packed:   50%  Max levels:  4
     - check data record references index: 3
     Key:  3:  Keyblocks used:  97%  Packed:    0%  Max levels:  4
     - check data record references index: 4
     Key:  4:  Keyblocks used:  99%  Packed:   60%  Max levels:  3
     - check data record references index: 5
     Key:  5:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     - check data record references index: 6
     Key:  6:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     - check data record references index: 7
     Key:  7:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     - check data record references index: 8
     Key:  8:  Keyblocks used:  99%  Packed:    0%  Max levels:  3
     - check data record references index: 9
     Key:  9:  Keyblocks used:  98%  Packed:    0%  Max levels:  4
     Total:    Keyblocks used:   9%  Packed:   17%
     
     - check records and index references
     [LOTS OF ROW NUMBERS DELETED]
     
     Records:          1403698    M.recordlength:     226   Packed:             0%
     Recordspace used:     100%   Empty space:          0%  Blocks/Record:   1.00
     Recordblocks:     1403698    Deleteblocks:         0
     Recorddata:     317235748    Deleted data:         0
     Lost space:             0    Linkdata:             0
     
     User time 1639.63, System time 251.61
     Maximum resident set size 0, Integral resident set size 0
     Non physical pagefaults 0, Physical pagefaults 10580, Swaps 0
     Blocks in 4 out 0, Messages in 0 out 0, Signals 0
     Voluntary contexts switches 10604, Involuntary contexts switches 122798

   Here are the data file sizes of the table used above.
     -rw-rw-r--   1 monty    tcx     317235748 Jan 12 17:30 company.ISD
     -rw-rw-r--   1 davida   tcx      96482304 Jan 12 18:35 company.ISM

   Explanations for the things `isamchk' prints:
`ISAM file'
     Name of isam file.

`Isam-version'
     Version of isam format. Currently always 2.

`Creation time'
     When was the data file created.

`Recover time'
     When was the index/data file last reconstructed.

`Data records'
     How many records/rows.

`Deleted blocks'
     How many deleted blocks still have reserved space. *Note Repair::.

`Datafile: Parts'
     For dynamic record format this shows how many data blocks there
     are. For an optimised table without splits this is the same as
     `Data records'.

`Deleted data'
     How many bytes of non-reclaimed deleted data.

`Datafile pointer'
     Size (in bytes) of the datafile pointer. It is usually 2, 3, 4 or 5
     bytes. Most tables manage with 2 bytes but this cannot be
     controlled from *MySQL* yet. For fixed tables this is a record
     address. For dynamic tables this is a byte address.

`Keyfile pointer'
     How many bytes has the datafile pointer. It is usually 1, 2 or 3
     bytes. Most tables manage with 2 bytes but this is calculated
     automatically by *MySQL*. It is always a block address.

`Max datafile length'
     How long (in bytes) can the table's data file (`.ISD') get.

`Max keyfile length'
     How long (in bytes) can the table's key file (`.ISM') get.

`Recordlength'
     How much space does each record/row take.

`Record format'
     Which format does each record/row have. This example uses `Fixed
     length'.

`table description'
     A list of all keys in the table. For each key some low level
     information is presented.

`Key'
     This key's number.

`Start'
     Where in the record/row does this index-part start.

`Len'
     How long is this index part. For packed numbers this should always
     be the full length of the column. For strings it may be shorter
     than the full length.

`Index'
     `unique' or `multip.'. If one value can exist multiple times in
     this index.

`Type'
     What data-type does this index part have. This is a `C' data-type
     with the options packed, stripped or empty.

`Root'
     Address of the root index block.

`Blocksize'
     The size of each index block. This is by default 1024 but may be
     changed at compile time.

`Rec/key'
     This is a statistical value used by the optimiser. It tells how
     many records there are per value for this key. A unique key always
     has a value of 1. This may be updated after a table is loaded (or
     greatly changed) with `isamchk -a'. If this is not updated at all,
     a default value of 30 is given.

`'
     The 9th key is a multi-part key with two parts.

`Keyblocks used'
     What percentage of the keyblocks are used. Since this table has
     just been reorganised with isamchk the values are very high (very
     near theoretical maximum).

`Packed'
     *MySQL* tries to pack keys with a common suffix. This can only be
     used for `CHAR'/`VARCHAR'/`DECIMAL' keys. For long strings like
     names, this can significantly reduce the space used. In the above
     example the 4th key is 10 characters long and gets a 60% reduction
     in space.

`Max levels'
     How deep is the btree for this key. Large tables with long keys
     get high values.

`Records'
     How many rows does the table have.

`M.recordlength'
     Average recordlength. For fixed tables this is the recordlength.

`Packed'
     *MySQL* strips spaces from the end of strings. What percentage did
     we save by doing this.

`Recordspace used'
     What percentage of the datafile is used.

`Empty space'
     What percentage of the datafile is unused.

`Blocks/Record'
     How many blocks are there per record. This is always 1 for fixed
     format tables. This value should stay as close to 1.0 as possible.
     If it gets too big you can reorganise the table with `isamchk'.
     *Note Repair::.

`Recordblocks'
     How many blocks are used. For fixed format, this is the same as
     the number of records.

`Deleteblocks'
     How many blocks are deleted.

`Recorddata'
     How many bytes of actual user data there are in the datafile.

`Deleted data'
     How many bytes of deleted data there are in the datafile.

`Lost space'
     If a record is updated to a shorter length, some space is lost.
     This is the sum of all such losses.

`Linkdata'
     When the dynamic format is used, blocks are linked with pointers
     (length 4-7 bytes). This is the sum of all such pointers.

The *MySQL* compressed read only table generator
================================================

   `pack_isam' is an extra that you get when ordering more than 10
licenses or extended support. Since `pack_isam' is distributed binary
only, `pack_isam' is only available on some platforms.

   Of course, all future updates to `pack_isam' is included in the
price. `pack_isam' may at some time be included as standard when we get
some kind of turnover for *MySQL*.

   `pack_isam' works by compressing each column in the table
separately. The information needed to decompress is read into memory
when the table is opened. This gives a much better performance when
accessing individual records as one only has to uncompress exactly one
record, not a much larger disk block like when using Stacker on MSDOS.

   *MySQL* uses memory mapping (mmap) on compressed tables and falls
back to normal read/write file usage if mmap doesn't work.

   Usually, `pack_isam' packs the datafile 40-70%.

   There is currently two limitations with `pack_isam':
     After packing, the table is read only.

   * It can't pack blobs, yet.

   Fixing these limitations is on our TODO but with low priority.

   `pack_isam' options:

     > pack_isam --help
     pack_isam Ver 5.0 for SOLARIS 2.5 on SPARCstation
     Copyright (C) 1994-1997 TcX AB & Monty Program KB & Detron HB.
     This is not free software. You must have a license to use this program
     This software comes with ABSOLUTELY NO WARRANTY
     
     Pack an ISAM-database to take much smaller space
     Keys are not updated, one must run isamchk -rq on datafile afterwards
     Usage: pack_isam [OPTIONS]
     
       -b, --backup          Make a backup of the table as table_name.OLD
       -f, --force           Force packing of table even if it's gets bigger or
                             tempfile exists.
       -j, --join=#          Join all given tables into table.
                             All tables MUST be identical.
       -p, --packlength=#    Force storage size of recordlength (1,2 or 3)
       -s, --silent          Be more silent.
       -t, --test            Don't pack table only test packing it
       -v, --verbose         Write info about progress and packing result
       -w, --wait            Wait and retry if table is in use
       -T, --tmp_dir=#       Use temporary directory to store temporary table
       -#, --debug=...       output debug log. Often this is 'd:t:o,filename`
       -?, --help            display this help and exit
       -V, --version         output version information and exit

   Typical run:

     (/my/monty/tmp) ls -l station.*
     -rw-rw-r--   1 monty    my         994128 Apr 17 19:00 station.ISD
     -rw-rw-r--   1 monty    my          53248 Apr 17 19:00 station.ISM
     -rw-rw-r--   1 monty    my           5767 Apr 17 19:00 station.frm
     
     (/my/monty/tmp) isamchk -dvv station
     
     ISAM file:     station
     Isam-version:  2
     Creation time: 1996-03-13 10:08:58
     Recover time:  1997-02-02  3:06:43
     Data records:              1192  Deleted blocks:              0
     Datafile: Parts:           1192  Deleted data:                0
     Datafilepointer (bytes):      2  Keyfile pointer (bytes):     2
     Max datafile length:   54657023  Max keyfile length:   33554431
     Recordlength:               834
     Record format: Fixed length
     
     table description:
     Key Start Len Index   Type                       Root  Blocksize    Rec/key
     1   2     4   unique  unsigned long              1024       1024          1
     2   32    30  multip. text                      10240       1024          1
     
     column Start Length Type
     1     1     1
     2     2     4
     3     6     4
     4     10    1
     5     11    20
     6     31    1
     7     32    30
     8     62    35
     9     97    35
     10    132   35
     11    167   4
     12    171   16
     13    187   35
     14    222   4
     15    226   16
     16    242   20
     17    262   20
     18    282   20
     19    302   30
     20    332   4
     21    336   4
     22    340   1
     23    341   8
     24    349   8
     25    357   8
     26    365   2
     27    367   2
     28    369   4
     29    373   4
     30    377   1
     31    378   2
     32    380   8
     33    388   4
     34    392   4
     35    396   4
     36    400   4
     37    404   1
     38    405   4
     39    409   4
     40    413   4
     41    417   4
     42    421   4
     43    425   4
     44    429   20
     45    449   30
     46    479   1
     47    480   1
     48    481   79
     49    560   79
     50    639   79
     51    718   79
     52    797   8
     53    805   1
     54    806   1
     55    807   20
     56    827   4
     57    831   4
     
     Compressing station.ISD: (1192 records)
     - Calculating statistics
     
     normal:     20  empty-space:      16  empty-zero:        12  empty-fill:  11
     pre-space:   0  end-space:        12  intervall-fields:   5  zero:         7
     Original trees:  57  After join: 17
     - Compressing file
     87.14%
     
     (/my/monty/tmp) ls -l station.*
     -rw-rw-r--   1 monty    my         127874 Apr 17 19:00 station.ISD
     -rw-rw-r--   1 monty    my          55296 Apr 17 19:04 station.ISM
     -rw-rw-r--   1 monty    my           5767 Apr 17 19:00 station.frm
     
     (my/monty/tmp) isamchk -dvv station
     
     ISAM file:     station
     Isam-version:  2
     Creation time: 1996-03-13 10:08:58
     Recover time:  1997-04-17 19:04:26
     Data records:              1192  Deleted blocks:              0
     Datafile: Parts:           1192  Deleted data:                0
     Datafilepointer (bytes):      3  Keyfile pointer (bytes):     1
     Max datafile length:   16777215  Max keyfile length:     131071
     Recordlength:               834
     Record format: Compressed
     
     table description:
     Key Start Len Index   Type                       Root  Blocksize    Rec/key
     1   2     4   unique  unsigned long             10240       1024          1
     2   32    30  multip. text                      54272       1024          1
     
     Field Start Length Type                         Huff tree  Bits
     1     1     1      constant                             1     0
     2     2     4      zerofill(1)                          2     9
     3     6     4      no zeros, zerofill(1)                2     9
     4     10    1                                           3     9
     5     11    20     table-lockup                         4     0
     6     31    1                                           3     9
     7     32    30     no endspace, not_always              5     9
     8     62    35     no endspace, not_always, no empty    6     9
     9     97    35     no empty                             7     9
     10    132   35     no endspace, not_always, no empty    6     9
     11    167   4      zerofill(1)                          2     9
     12    171   16     no endspace, not_always, no empty    5     9
     13    187   35     no endspace, not_always, no empty    6     9
     14    222   4      zerofill(1)                          2     9
     15    226   16     no endspace, not_always, no empty    5     9
     16    242   20     no endspace, not_always              8     9
     17    262   20     no endspace, no empty                8     9
     18    282   20     no endspace, no empty                5     9
     19    302   30     no endspace, no empty                6     9
     20    332   4      allways zero                         2     9
     21    336   4      allways zero                         2     9
     22    340   1                                           3     9
     23    341   8      table-lockup                         9     0
     24    349   8      table-lockup                        10     0
     25    357   8      allways zero                         2     9
     26    365   2                                           2     9
     27    367   2      no zeros, zerofill(1)                2     9
     28    369   4      no zeros, zerofill(1)                2     9
     29    373   4      table-lockup                        11     0
     30    377   1                                           3     9
     31    378   2      no zeros, zerofill(1)                2     9
     32    380   8      no zeros                             2     9
     33    388   4      allways zero                         2     9
     34    392   4      table-lockup                        12     0
     35    396   4      no zeros, zerofill(1)               13     9
     36    400   4      no zeros, zerofill(1)                2     9
     37    404   1                                           2     9
     38    405   4      no zeros                             2     9
     39    409   4      allways zero                         2     9
     40    413   4      no zeros                             2     9
     41    417   4      allways zero                         2     9
     42    421   4      no zeros                             2     9
     43    425   4      allways zero                         2     9
     44    429   20     no empty                             3     9
     45    449   30     no empty                             3     9
     46    479   1                                          14     4
     47    480   1                                          14     4
     48    481   79     no endspace, no empty               15     9
     49    560   79     no empty                             2     9
     50    639   79     no empty                             2     9
     51    718   79     no endspace                         16     9
     52    797   8      no empty                             2     9
     53    805   1                                          17     1
     54    806   1                                           3     9
     55    807   20     no empty                             3     9
     56    827   4      no zeros, zerofill(2)                2     9
     57    831   4      no zeros, zerofill(1)                2     9

Adding functions to *MySQL*
***************************

Adding new functions to *MySQL*
===============================

   You have two ways to add new functions to mysql:
   * You can add the function trough the new UDF interface.  *Note UDF
     functions::

   * You can add this as a native *MySQL* function.

   To add a new native *MySQL* function (like `SOUNDEX()'), you only
have to do the following:

  1. Add one line in `sql_lex.cc' defining the function name in the
     `sql_functions' array.

  2. Add two lines in `sql_yacc.y'. On defines the preprocessor symbol
     yacc can define (this should be added at the beginning of the
     file). Then define the function parameters and create an 'item'
     with these parameters.  Check, for example, all occurrences of
     SOUNDEX in `sql_yacc.y'

  3. In item_func.h declare a class inheriting from Item_num_func or
     Item_str_func depending on whether your function returns a number
     or a string.

  4. In `item_func.cc' add: `double *Item_func_newname::val()' If you
     are defining a number function or `String
     *Item_func_newname::Str(String *str)' if you are defining a string
     function.

  5. You should probably also define the following function: `void
     Item_func_newname::fix_length_and_dec()' This should at least
     calcutate `max_length' based on the given arguments. `max_length'
     is the maximum number of chars the function may return. If the
     function can't return a `NULL', one should set `maybe_null = 0'.

   About string functions:
  1. For string functions the `String *str' argument provides a string
     buffer that may be used to hold the result.

  2. A string function should return the string that holds the result.

  3. All current string functions try to avoid allocating any memory
     unless absolutely necessary!

ODBC
****

Which operating systems does *MySQL* ODBC support?
==================================================

   *MySQL* ODBC is a 32 bit ODBC (2.50) level 0 driver for Windows95
and NT. We hope somebody will port it to Windows 3.x.

How should I report problems with *MySQL* ODBC?
===============================================

   We have only tested ODBC with Admndemo, some C programs, Msquery and
Excel.

   To give some light about any problem we would like to have the log
file from the ODBC manager (the log you get when requesting logs from
ODBCADMIN) and a MYODBC log.

   To get a MYODBC log, please add 4 to the 'Options' argument on the
MyODBC connect/configure screen.

   The log will be written to file `c:\tmp\myodbc.log'.

Programs known to work with MyODBC
==================================

   Most programs should work with MyODBC, but we we have tested these
ourselves or got a confirmation from some user that is works:

Program
     Comment

Access
     To make Access work:
        * You should have a primary key in the table.

        * You should have a timestamp.

        * Only use double float fields. Access fails when comparing
          with single floats.

        * Set 2 in the options field when connection to *MySQL*.

Excel
     Works. Some tips
        * If you have problems with dates try to select them as strings.
               SELECT concat(sunrise_time), concat(sunset_time) FROM sunrise_sunset;
          Values returned in this format (string) should be correctly
          recognised by Excel97 as time values.

          What `concat()' does in this case is that it fools ODBC to
          think the column is of 'string type'. Without the 'concat()'
          ODBC knows the column is of time type. Excel does not
          understand that.

          Note that this is a bug in Excel because it automatically
          converts a string to a time. This would be great if the
          source was a text file, but this is plain stupid when the
          source is a ODBC connection which reports exact types for
          each column.

odbcadmin
     Test program for ODBC.

Delphi
     One must use DBE 3.2 or newer.

C++Builder
     Tested with BDE 3.0. The only known problem is that when the table
     schema changes, query fields are not updated. BDE however does not
     seem to recognise primary keys, only the index PRIMARY, though
     this has not been a problem.

How do I fill in the various fields in the ODBC administrator program?
======================================================================

   There are three possibilities for specifying the server name on
Windows95:

  1. Use the IP address of the server.

  2. Add a file lmhosts with the following info: `ip hostname' For
     example:
          194.216.84.21 my

  3. Configure the PC to use DNS.

   Example of how to fill in the 'ODBC setup'.
     Windows DNS name:   test
     Description:        This is my test database
     MySql Database:     test
     Server:             194.216.84.21
     User:               monty
     Password:           my_password
     Port:

   The 'Windows DNS name' is any name that is unique in your windows
ODBC setup.

   When you fill in the values in the ODBC setup, these will be used as
default values when prompting for a Driver connect. You don't have to
give 'server', 'user' or 'password' in the ODBC setup screen.

   When connecting to an ODBC source you have the option to change the
server, user, password and port.

   If port is not given the default port (3306) is used.

How to get the value of a AUTO_INCREMENT column in ODBC
=======================================================

   A common problem is how to get the value of an
automatically-generated id from an `INSERT'. With ODBC you can do
something like this:

     INSERT INTO foo (auto,text) VALUES(NULL,'text')
     select LAST_INSERT_ID()

   or if you are just going to insert in into another table:

     INSERT INTO foo (auto,text) VALUES(NULL,'text')
     INSERT INTO foo2 (id,text) VALUES(LAST_INSERT_ID(),'text')

   For the benefit of some ODBC applications (at least Delphi and
Access) the following query can be used to find a newly inserted row:
     SELECT * from table_name WHERE auto_increment_column IS NULL

Problems and common errors
**************************

Some common errors when using *MySQL*
=====================================

`MySQL server has gone away' error
----------------------------------

   The most common reason for the `MySQL server has gone away' error is
that the server closed the connection because of a timeout. By default
the server closes the connection after 8 hours if nothing has happened.

   If you have a script you just have to issue the query again for the
client to do a automatically reconnection.

   One normally can get these error codes in this case: (Which one you
get is OS dependent)

CR_SERVER_GONE_ERROR   The client couldn't send a question to the server. 
CR_SERVER_LOST         The client didn't get an error when writing to     
                       the server but it didn't get full answer (or any   
                       answer) to the question.                           

   You can also get this error if you send a wrong or too big query to
the server. If mysqld gets a wrong block it assumes that something has
gone wrong with the client and closes the connection.  If you need big
queries, if you are for example working with  big blobs, you can
increase the query limit by starting mysqld with the option `-O
max_query_size=#' (default 65536). The extra memory is allocated by
demand, so mysqld will only use more memory when you issue a big query
or when mysqld must return a big result row!

`Can't connect to local MySQL server' error
-------------------------------------------

   A *MySQL* client can connect to the mysqld server in two different
ways:  Unix sockets, which connects trough a file in the file system,
(default `/tmp/mysqld.sock'), or TCP/IP which connects trough a port
number.  Unix sockets are faster than TCP/IP but can only be used when
connection to a server on the same computer.  Unix sockets are used if
one doesn't specify a hostname or if one specifies the special hostname
'localhost'.

   Here follows some reasons to the error `Can't connect to local MySQL
server'.

   * You don't have a mysqld running.  Check that you have a process
     named 'mysqld' running with `ps'.  You can check the server by
     trying these different connections: (the port and socket may of
     course be different in your setup).

          mysqladmin version
          mysqladmin -h `hostname` version
          mysqladmin -h `hostname` --port=3306 version
          mysqladmin --socket=/tmp/mysql.sock version

   * You are running on a system that uses MIT-pthreads.  MIT-pthreads
     doesn't support sockets.  If you are running on a system that
     doesn't have native threads mysqld uses the MIT-pthreads package.
     *Note Which OS::.

     When using MIT-pthreads you must always give the hostname when
     connecting to the server.  Try using `'mysqladmin -u `hostname`
     version' to check the connection to the server.

   * Someone has removed the unix socket mysqld uses.  You may have a
     cron job that removes the mysql socket (default
     `/tmp/mysqld.sock').  You can always run `mysqladmin version' and
     check that the socket mysqladmin is trying to use really exists.
     The fix in this case is to change the cron job not to remove
     mysqld.sock or to place the socket somewhere else. You can move
     the socket by reconfiguring mysqld with `./configure
     --with-unix-socket-path=/my-own-place/mysql.sock' or starting
     safe_mysqld with `--socket=/my_own_place/mysqld.sock' and setting
     the environment variable `MYSQL_UNIX_PORT' to point at the socket
     before starting your mysql clients.

   * You have started the mysqld server with `--socket=...'.  If you
     change the socket you must also notify the clients about the new
     path. You can do this by setting the environment variable
     `MYSQL_UNIX_PORT' to point at the socket or provide the socket as a
     argument to the mysql clients. You can for example test the socket
     with `mysqladmin --socket=/path-to-socket version'.

Out of memory errors
--------------------

   If you do a query and get something like the following error:

     mysql: Out of memory at line 42, 'malloc.c'
     mysql: neaded 8136 byte (8k), memory in use: 12481367 bytes (12189k))
     ERROR 2008: *MySQL* client got out of memory

   Note that the error refers to the *MySQL* client. The reason for
this error is simply that the client does not have enough memory to
store the whole result.

Packet to large
---------------

   When the client gets a block bigger that `net_buffer_length' it
issues a `Packet too large' error.

   If the `mysql' client is used you may set a bigger buffer by
starting the client with `mysql --set-variable= net_buffer_length=1m'.

The table is full
-----------------

   This error occurs when an in-memory temporary table gets bigger than
`tmp_table_size'. To avoid this problem one can increase the `-O
tmp_table_size=#' option to mysqld or use the SQL option
`SQL_BIG_TABLES' before you do the problem query. *Note Set option::.

   One can also start mysqld with the option: `--big-tables'.  This is
exactly the same as using SQL_BIG_TABLES for all queries.

Commands out of sync in client
------------------------------

   If you get `Commands out of sync; You can't run this command now' in
youe client code, you are calling clients functions in the wrong order!

   This can for example happen if you are using 'mysql_use_result()'
and try to execute a new query before you have done a
'mysql_free_result()'.  This can also happen if you try to execute two
queries, that returns data, without a mysql_use_result() or
mysql_store_result() between.

Removing user
-------------

   If you get the following error:

   `Found wrong password for user: 'XXX@localhost'; Removing user'

   This means that mysqld on start or 'reload' found and entry in the
user table that didn't have a legal password.

   The row is not removed from the user table, it's only not used by the
permission system

   Possible causes and fixes for this:

   * This means that you are running a new mysqld version with an old
     user table; You can verify this by doing a 'mysqlshow mysql user'
     and check if the password field is shorter than 16 characters. You
     can correct this by running the `scripts/add_long_password'

   * The user has an old password (8 char long) and you didn't start
     mysqld with -old-protocoll; Update the user in the user table with
     a new password or restart mysqld with -old-protocol.

   * You have specified a password in the user table without the
     PASSWORD() function; Update the user in the user table with a new
     password in `mysql': `UPDATE user set password=password('your
     password') where user='XXX''

How does *MySQL* handle a full disk
===================================

   On a disk full condition *MySQL* does the following:

     It checks once every minute if there is enough space to write the
     current row. If there is enough disk it continues as if nothing had
     happened.

   * Every 6 minutes it writes a entry to the log file warning about
     disk full.

   * To continue you have only to free enough free space to insert all
     records.

   * To abort the thread you have to send a `mysqladmin kill' to the
     thread.  The thread will be aborted when it checks the disk next
     time (in 1 minute).

   * Note that other threads may be waiting for the table that caused
     'disk full'.  If you have a lot of 'locked' threads killing the
     one thread that waits for disk full will allow the other threads
     to continue.

Where *MySQL* stores temporary files
====================================

   *MySQL* uses the value of the TMPDIR environment variable as where to
store temporary files. If you don't have TMPDIR set, *MySQL* will use
the system default, normally `/tmp or /usr/tmp'.  If your TMPDIR is too
small, you should edit safe_mysqld to set TMPDIR to point at some
directory where you have enough space!  One can also use the `--tmpdir'
option for `mysqld' to set the temporary directory.

   *MySQL* creates all temporary files as 'hidden files'. This ensures
that the temporary files will be removed if mysqld is terminated.  The
'bad' side with using hidden files is that you will not see a big
temporary file that fills up a too small temporary disk.

   When sorting (ORDER BY or GROUP BY) *MySQL* normally uses one or two
temporary files. The maximum disk-space needed is
`(length_of_what_is_sorted + sizeof(database_pointer)) *
number_of_matched_rows * 2'. `sizeof(database_pointer)' is usually 4 but
may grow in the future for really big tables.

   For some SELECT queries will also create temporary SQL tables. These
are not hidden and will have a name that starts with SQL_.

   `ALTER TABLE' will create a temporary table in the same directory as
the original table.

`Access denied?' error
======================

   *Note Privileges::. And especially *Note Access denied::.

How to run *MySQL* as a normal user
===================================

   mysqld (the *MySQL* server) can be started and run by any user.  In
order to change mysqld to run as user USER, you'd have to the following:

   * Stop the server if it's running

   * Change the database directories so that USER has read and write
     privileges privileges to them: `shell> chown -R USER
     /your/path/to/mysql/var'

   * start the server as user USER or if you are using *MySQL* 3.22
     start mysqld as root and use the -user='name of user' switch.
     mysqld will switch to run as the given user before accepting any
     connections.

   * If you are using mysql.server to start mysqld when the system is
     rebooted, you should change mysql.server to call 'su' to user USER
     or use the -user switch.

   *  You don't have to do anything to safe_mysqld to not run as root.

   At this point, your mysqld process should be running fine and dandy
as user 'USER'. One thing hasn't changed though - the access
permissions. By default (right after running the permissions table
install script), only user 'root' has access permission to the database.
Unless you have changed that, it's still true. This shouldn't stop you
from accessing *MySQL* when you're logged in under a user other than
root, just specify -u root to the client program. Note that accessing
*MySQL* as root, by supplying -u root in the command line, doesn't have
ANYTHING to do with *MySQL* running as root, as a user or as anyone
else. The access permissions and userbase of *MySQL* are completely
separate from the UNIX users. The only connection to the UNIX users is
if you don't use the -u option to clients. In this case the client will
try to login into *MySQL* with your UNIX login name. If your UNIX box
itself isn't secured, you should probably at least put a password on
the root users in the *MySQL* access tables, since any johndoe user can
run 'mysql -u root dbname' and do whatever he likes.

Problems with file permissions
==============================

   If you have problems with file permissions, for example when
creating a table mysql gives: "ERROR: Can't find file:
'path/with/filename.frm' (Errcode: 13)", then you might have the wrong
value for environment variable UMASK.  Default umask is 0664. Fix:
     UMASK=432
     export UMASK
     ./bin/safe_mysqld

File not found
==============

   If you get `ERROR '...' not found (Errcode: 23)' or any other error
with `errcode 23' from *MySQL* this means that you haven't allocated
enough file descriptors for *MySQL*.  `perror #' will give you the
error message in a more readable form.

   There is a commented line `ulimit -n 256' in `safe_mysqld'. You can
remove this comment and of course increase or decrease the value if you
want. You can also make the table cache smaller with: `safe_mysqld -O
table_cache=32' (the default is 64).

Problems using DATE columns
===========================

   The format of DATE is 'YYYY-MM-DD'. According to ANSI SQL nothing
else is allowed. One should use this format to update or in the WHERE
clause, ie `select * from table_1 where date >= '1997-05-05'';

   As a convenience, *MySQL* automatically converts the date to a
number if used in a number context. It is also smart enough to allow a
'relaxed' string form when updating and in a `WHERE' with a compare to
a `TIMESTAMP', `DATE' or a `DATETIME' column.

   The special date '0000-00-00' can be stored and retrieved as
0000-00-00.  When using a '0000-00-00' date trough MyODBC it will
automatically be converted to NULL in MyODBC 2.50.12 and above, because
ODBC can't handle this kind of dates.

   This means that the following works:

     insert into table_1 (idate) values (19970505) ;
     insert into table_1 (idate) values ('19970505') ;
     insert into table_1 (idate) values ('97-05-05');
     insert into table_1 (idate) values ('1997.05.05');
     insert into table_1 (idate) values ('1997 05 05');
     insert into table_1 (idate) values ('0000-00-00');
     
     select idate from table_1 where idate >= '1997-05-05';
     select idate from table_1 where idate >= 19970505;
     select mod(idate,100)1 from table_1 where idate >= 19970505;
     select idate from table_1 where idate >= '19970505';

   The following will not work:

     select idate from table_1 where strcmp(idate,'19970505')=0;
     Because '19970505' is compared as a string to '1997-05-05'.

   Note that *MySQL* does no checking if the date is correct.  If you
store a wrong date, like 1998-2-31, the wrong date will be stored. If
the date is totally impossible a 0 is stored in the date field..  This
is mainly a speed issue and we think it's up to the application to
check the dates and not the server.

Case sensitivity in searches.
=============================

   By default a *MySQL* column is case insensitive (although there are
some character sets that never are case insensitive). That means that
if you search with `column like 'a%';' you will get all columns that
start with `A' or `a'. If you want to make this search case sensitive
use something like `INDEX(column, "A")=0' to check a prefix. Or
`STRCMP(column, "A") = 0' if the whole string should be the same.

   Simple compare operations `>=, >, = , < , <=', sorting and grouping
are done on the characters 'sort value'. Characters with the same sort
value (like E, e and ) are treated as the same character!

   LIKE comparing is done on the uppercase value of each character (E
== e but E <> )

   If you want `column' to always be treated in a case sensitive manner,
declare it as `BINARY'. *Note Create table::.

   If you are using Chinese data in the so-called big5 encoding you
want to make all character columns `BINARY'. This works because the
sorting order of big5 encoding characters is based on the order of
ascii codes.

Problems with NULL
==================

   A common confusion for newcomers to SQL is that they think that NULL
is the same things as a empty string ".  This is not the case! For
example the following statements are compleatly different:

     INSERT INTO my_table (name,phone) values ("my",NULL);
     INSERT INTO my_table (name,phone) values ("my","");

   The first inserts a NULL value into address and the second inserts
an empty string into address.  The first can be regarded as 'phone
number is not known' and the second can be regarded as 'she has no
phone'.

   In SQL NULL is a value that is always false when comparing to all
other values, even NULL.  An expression that contains NULL will always
produce a NULL value if nothing else is mentioned. All following
columns return NULL:

     SELECT NULL,1+NULL,CONCAT('Invisible',NULL);

   If you want to search for a column that has NULL, you must use the
IS NULL test.  The following shows how to find the NULL phone number and
the empty phone number:

     SELECT * from my_table where phone IS NULL;
     SELECT * from my_table where phone = "";

   In *MySQL*, as in many other SQL servers, you can't index columns
that can have `NULL' values.  You have to declare such columns `NOT
NULL'.

   When reading data with `LOAD DATA INFILE' empty columns are updated
with ". If you want a NULL value in a column you should use NULL or \N
in the textfile.

   When using `ORDER BY' NULL values are presented first (if not using
DESC).  When using `GROUP BY' all NULL values are regarded as equal.

   To help with NULL handling you can use the functions: `IS NULL', `IS
NOT NULL' and `IFNULL()'

Solving some common problems with *MySQL*
*****************************************

Database replication
====================

   The most general way to do database replication is using the update
log. *Note Update log::. This requires that one database acts as a
master (all data changes are done here) and one or more others as
slaves. To update a slave just run `mysql < update_log'.

   If you never do deletes, you can use timestamps.

   It is possible to make a two-way updating system using both the
update log (for deletes) and timestamps (on both sides). But in that
case you must be able to handle confilicts when the same data has been
changed in both ends. You probably want to keep the old version to help
with deciding what has been updated.

   Because replication in this case is done with SQL statements, you
should not use the following functions in statements that updates the
database, because they may return a different value in the other
*MySQL* server:

   * DATABASE()

   * GET_LOCK() and RELEASE_LOCK().

   * RAND()

   * USER(), SYSTEM_USER() or SESSION_USER().

   * VERSION()

   All time functions are safe to use as the timestamp is sent to the
mirror if needed. LAST_INSERT_ID() is also safe to use.

Backup of databases
===================

   Since *MySQL* tables are stored as files it is easy to do a backup.
To get a consistent backup, do a `LOCK TABLES' on the relevant tables.
*Note Lock tables::. You only need a read lock so other threads can
continue to query the tables while making a copy of the files in the
database directory. Or if you want to make a SQL level backup you can
use `SELECT INTO OUTFILE'.

   Another way is to use the `mysqldump' program.

     Do a full backup of your databases, with `mysqldump --tab=some-dir
     --lock-tables --quick ' or simply by copying all table files
     (.frm, .ISM and .ISD) while the server isn't updating anything.

   * start `mysqld' with `--log-update'

   * You will get log files with name of 'hostname'.# where # is a
     number that is increased for each reload.

   When you have to restore something (if `isamchk -r' can't restore
all data as it can in 99.9% of all cases):

   * Restore the original mysqldump backup.

   * ls -1 -t -r hostname.* | xargs cat | mysql

   The ls in the last command is done to get all log files in the right
order

   You can also do selective backups with `select * into outfile from
table' and restore with `LOAD DATA FROM INFILE 'file_name' REPLACE
...'. To avoid duplicate records you need a `PRIMARY KEY' in the table.
The `REPLACE' means that if there is a 'duplicate index' conflict when
inserting new records the old record will be replaced with the new one.

*MySQL* client tools and API's
******************************

*MySQL* C API
=============

   The `C' API is distributed with *MySQL*. It is included in the
`libmysqlclinet' library. It allows `C' programs to access a database.

   Most of the other client APIs (all except Java) use this library to
connect. So for example you can use the same environment variables.

   The client has a maximum communication buffer size. This is
automatically increased up to the maximum size (the default for this is
512Kb). As buffers are increased (but not decreased until close) on
demand, it will not take any resources if one increases this. This size
check is mostly a check for erroneous queries and communication packets.

   The communication buffer must be big enough to contain a single SQL
statement and one row of returned data (but of course not at the same
time). Each thread's communication buffer is dynamically enlarged to
handle any row or query up to the imposed limit.

   So if you have `BLOB's that contains data up to 16M you must have at
least 16M as your communication buffer limit. *Note MySQL parameters::.

   *MySQL* shrinks each communication buffer to `net_buffer_length'
after each query.

*mysql_affected_rows*   Retrieves the number of affected rows by the      
                       last UPDATE, DELETE or INSERT.                     
*mysql_close*           Closes a server connection.                       
*mysql_connect*         Establish a connection to a *MySQL* server.       
*mysql_create_db*       Create a database.                                
*mysql_data_seek*       Seeks to an arbitrary row in a query result set.  
*mysql_drop_db*         Drop a database.                                  
*mysql_eof*             Determine if last row has been read.              
*mysql_escape_string*   Escape a string for a SQL statement.  *Note Base  
                       Syntax::                                           
*mysql_error*           The error message from last *MySQL* function.     
*mysql_fetch_field*     Find out what type a table field is.              
*mysql_fetch_lengths*   Returns the length of all columns in a query      
                       result set.                                        
*mysql_fetch_row*       Fetch the 'next' row in the query result.         
*mysql_field_seek*      Put the column cursor on column number field.     
*mysql_free_result*     Free memory used to store a query result.         
*mysql_get_client_info* Return version information for the current        
                       client library.                                    
*mysql_get_host_info*   Returns name of server host.                      
*mysql_get_proto_info*  Get protocol version used by connection.          
*mysql_get_server_info* Returns the version number of the server.         
*mysql_insert_id*       Returns ID generated for a AUTO_INCREMENT field.  
*mysql_list_dbs*        Return matching database names.                   
*mysql_list_fields*     Return matching field names.                      
*mysql_list_processes*  Get a list of the current server threads.         
*mysql_list_tables*     Return matching table names.                      
*mysql_num_fields*      Return the number of columns in a result set.     
*mysql_num_rows*        Returns the number of rows in result set.         
*mysql_query*           Executes a SQL query.                             
*mysql_real_query*      Executes a SQL query with length information.     
*mysql_reload*          Reload the user permissions table in the server.  
*mysql_select_db*       Connect to a database.                            
*mysql_shutdown*        Shut down the database server.                    
*mysql_stat*            Return server status in a string.                 
*mysql_store_result*    Reads a result set to the client.                 
*mysql_use_result*      Initiate a dynamic result set for each row. This  
                       uses much less memory than `mysql_store_result()'  
                       but will put more strain on the server.            

`int *mysql_affected_rows*(MYSQL *mysql)'
     Retrieves the number of affected rows by the last UPDATE, DELETE
     or INSERT.

`void *mysql_close*(MYSQL *mysql)'
     Closes a server connection.

`MYSQL **mysql_connect*(MYSQL *mysql, const char *host, const char *user, const char *passwd)'
     Establish a connection to a *MySQL* server.

`int *mysql_create_db*(MYSQL *mysql, const char *db)'
     Create a database.

`void *mysql_data_seek*(MYSQL_RES *res, uint offset)'
     Seeks to an arbitrary row in a query result set.

`int *mysql_drop_db*(MYSQL *mysql, const char *db)'
     Drop a database.

`int *mysql_eof*(MYSQL_RES *)'
     Determine if last row has been read.

`char **mysql_error*(MYSQL *mysql)'
     The error message from last *MySQL* function.

`uint *mysql_escape_string*(char *to,char *from,uint length)'
     Escape a string for a SQL statement.

`MYSQL_FIELD **mysql_fetch_field*(MYSQL_RES *handle)'
     Find out what type a table field is.

     When querying for the length of a `BLOB' without retreving a
     result, *MySQL* returns the 'default blob length', which is 8192,
     when doing a select on the table. When one retrevies a result,
     column_object->max_length contains the real max_length for the
     specific query.

     The 8192 size is chosen because *MySQL* doesn't know the max length
     for the `BLOB'. This should be made configurable sometime.

`unsigned int **mysql_fetch_lengths*(MYSQL_RES *mysql)'
     Returns the length of all columns in a query result set.

`MYSQL_ROW *mysql_fetch_row*(MYSQL_RES *mysql)'
     Fetch the 'next' row in the query result.

`void *mysql_field_seek*(MYSQL_RES *result, int field)'
     Put the column cursor on column number field.

`void *mysql_free_result*(MYSQL_RES *result)'
     Free memory used to store a query result. Must be called after you
     are finished with a result set..

`char **mysql_get_client_info*(void)'
     Return version information for the current client library.

`char **mysql_get_host_info*(MYSQL *mysql)'
     Returns name of server host.

`int *mysql_get_proto_info*(MYSQL *mysql)'
     Get protocol version used by connection.

`char **mysql_get_server_info*(MYSQL *mysql)'
     Returns the version number of the server.

`unsigned long *mysql_insert_id*(MYSQL *mysql)'
     Returns ID generated for AUTO_INCREMENT field. As the API returns a
     unsigned long one can't use this with `BIGINT' columns. In this
     case one has to use the `LAST_INSERT_ID()' SQL function.

`MYSQL_RES **mysql_list_dbs*(MYSQL *mysql, const char *wild)'
     Return matching database names.

`MYSQL_RES **mysql_list_fields*(MYSQL *mysql, const char *table, const char *wild)'
     Return matching field names.

`MYSQL_RES **mysql_list_processes*(MYSQL *mysql)'
     Get a list of the current server threads.

`MYSQL_RES **mysql_list_tables*(MYSQL *mysql, const char *wild)'
     Return matching table names.

`int *mysql_num_fields*(MYSQL_RES *result)'
     Return the number of columns in a result set.

`int *mysql_num_rows*(MYSQL_RES *result)'
     Returns the number of rows in result set.

`int *mysql_query*(MYSQL *mysql, const char *query)'
     Executes a SQL query.

`int *mysql_real_query*(MYSQL *mysql, const char *query, uint length)'
     Executes a SQL query with length information.

`int *mysql_reload*(MYSQL *mysql)'
     Reload the user permissions table in the server.

`int *mysql_select_db*(MYSQL *mysql, const char *db)'
     Connect to a database.

`int *mysql_shutdown*(MYSQL *mysql)'
     Shut down the database server.

`char **mysql_stat*(MYSQL *mysql)'
     Return server status in a string.

`MYSQL_RES **mysql_store_result*(MYSQL *mysql)'
     Reads a result set to the client.

`MYSQL_RES **mysql_use_result*(MYSQL *mysql)'
     Initiate a dynamic result set for each row.

Why is it that after `mysql_query()' returns success, `mysql_store_result()' sometimes returns NULL?
----------------------------------------------------------------------------------------------------

   It means one of the following:

  1. Malloc failure.

  2. The data couldn't be read (Error on connection).

  3. The statement was a statement which never returns data (`INSERT'
     or `UPDATE' or `DELETE').

   You can always check if the statement should have given a result by
checking that `mysql_num_fields(MYSQL *)' isn't 0. If this is 0 the
last query was a statement that does not return values. For example a
`INSERT' or a `DELETE'.

   You have got an error if `mysql_error(MYSQL *)' isn't empty!

What results can I get from a query?
------------------------------------

   `mysql_affected_rows(MYSQL *)' returns the number of affected rows
in the last query when doing an `INSERT', `UPDATE' or `DELETE'. Except,
if `DELETE' is used without a `WHERE' clause then the table is
truncated which is much faster! In this case it returns the number of
records affected as zero.

   `mysql_insert_id(MYSQL *)' returns the given ID of the last query
when inserting a row into a table with an `AUTO_INCREMENT' index.
*Note mysql_insert_id::

   Some queries, `LOAD DATA INFILE...' and `INSERT INTO ... SELECT
...', `UPDATE' return additional info.  The result is returned in
`mysql_info(MYSQL *)'. `mysql_info()' returns a null pointer if there
is no additional information.

How can I get the unique ID for the last inserted row?
------------------------------------------------------

   If you insert a record that has a `AUTO_INCREMENT' index then you
can get the given id with `mysql_insert_id(MYSQL *)'.

   The last value is also stored in the server and can be retrieved with
the `LAST_INSERT_ID()' function.

   You can check if an auto_increment index is used by the following
code. This also checks if the query was an `INSERT' with an
`auto_increment' index.

     if (mysql_error(MYSQL)[0] == 0 &&
         mysql_num_fields(MYSQL_RESULT) == 0 &&
         mysql_insert_id(MYSQL) != 0)
       used_id = mysql_insert_id(MYSQL);

   The id that `LAST_INSERT_ID()' returns is maintained in the server
per connection. It will not be botched by another client. It will not
even be changed if you update another auto_increment column with a non
magic value (that is a not NULL or 0).

What is the difference between `mysql_use_result()' and `mysql_store_result()' modes?
-------------------------------------------------------------------------------------

   `mysql_use_results' reads the result directly from the server without
storing it in a temporary table or local buffer. This is somewhat faster
and uses much less memory than `mysql_store_result'. One shouldn't use
`mysql_use_results' if there is a lot of processing being done for each
row at the client side, or if the output is sent to a screen on which
the user may do a ^S (stop scroll). Doing this would tie up the server
and then other threads couldn't update the used tables. One can't use
`mysql_data_seek' `mysql_num_rows' or issue other queries while using
`mysql_use_result'.

   When using `mysql_use_result' one must execute `mysql_fetch_row()'
until one gets a NULL pointer back, because else the next query would
get results from the previous query. The C API will give the error:
`Commands out of sync;  You can't run this command now', if you forget
to do this!

Problems linking with the C API
-------------------------------

   When linking with the C API you can get the following errors on some
systems:

     gcc -g -o client test.o -L/usr/local/lib/mysql -lmysqlclient -lsocket -lnsl
     
     Undefined        first referenced
      symbol          in file
     floor            /usr/local/lib/mysql/libmysqlclient.a(password.o)
     ld: fatal: Symbol referencing errors. No output written to client

   This means that on your system you have to include the math library
(-lm) last in the compile/link line.

How to make a threadsafe client
-------------------------------

   The client is 'almost' thread-safe. The biggest problem is that
net.c (the subroutines that read from sockets) are not interrupt safe.
This was done with the thought that one may want to have one's own alarm
that can break a long read to a server.

   The standard client libraries are not compiled with the thread
options.

   To get a thread safe client use the `-lmysys', `-lstring' and
`-ldbug' libraries and `net_serv.o' that the server uses.

   When using a threaded client one can have great use of the
thr_alarm.c routine. If you are using the mysys routines, the only
thing one has to remember is to call my_init() first!

   All functions except mysql_connect() are currently thread safe.

   To get connect thread_safe you have to do the following:

   Recompile the client with:

     CPPFLAGS=-DTHREAD_SAFE_CLIENT ./configure ...

   You may get some errors because of undefined symbols when linking the
standard client as the pthread libraries are not included by default.

   The resulting libmysqld.a library is now thread safe.

   Two threads can't use the same handle (returned by
`mysql_connect()') at the same time, even if two threads can use
different `MYSQL_RES' handles that were created with
`mysql_store_result()'.

*MySQL* Perl API's
==================

   Since `DBI/DBD' now is the recommended perl interface mysqlperl is
not documented here.

`DBI' with `DBD::mysql'
-----------------------

   `DBI' is a generic interface for many databases. That means that you
can write a script what works with many different database engines
without change. You need a DataBase Driver (DBD) defined for each
database type. For *MySQL*, this driver is called `DBD::mysql'.

   For more information on the Perl5 DBI, please visit
DBIs web page (http://www.hermetica.com/technologia/DBI/) and read the
documentation. For more information on Object Oriented Programming
(OOP) as defined in Perl5, see
the perl OOP page (http://language.perl.com/info/documentation.html).

The DBI interface
.................

   *Portable DBI methods.*

connect                Establish a connection to a database server        
prepare                Get a SQL statement ready for execution            
do                     Prepares and executes a SQL statement              
disconnect             Disconnect from the database server                
quote                  Quote strings/blobs to be inserted                 
execute                Executes prepared statements                       
fetchrow_array         fetch the next row as an array of fields.          
fetchrow_arrayref      fetch next row as a reference array of fields      
fetchrow_hashref       fetch next row as a reference to a hashtable       
fetchall_arrayref      Get all data as a array of arrays                  
finish                 finish a statment and let the system free          
                       resources                                          
rows                   Returns the number of rows affected                
data_sources           Return an array of databases available on          
                       localhost                                          
ChopBlanks             Shall fetchrow trim spaces                         
NUM_OF_PARAMS          Number of placeholders in the prepared statement   
NULLABLE               Which columns can be NULL                          

   *MySQL specific methods.*

insertid               The latest auto_increment value                    
is_blob                Which column ar BLOBs                              
is_key                 Which columns are keys                             
is_num                 Which columns are numeric                          
is_pri_key             Which columns are primary keys                     
is_not_null            Which columns can NOT be NULL. See NULLABLE        
length                 Maximum theoretically possible column sizes        
max_length             Maximum physical present column sizes              
NAME                   Column names                                       
NUM_OF_FIELDS          Number of fields returned.                         
table                  Table names in returned set                        
type                   All coulumn types                                  
_CreateDB              Create a database                                  
_DropDB                Drop a database. *THIS IS DANGEROUS*               

`connect'
     You use the connect method to make a database connection to the
     data source. The `$data_source' value should begin with
     `DBI:driver_name:'.  Example connect methods with the `DBD::mysql'
     driver:
          $dbh = DBI->connect("DBI:mysql:$database", $user, $password);
          $dbh = DBI->connect("DBI:mysql:$database:$hostname",
                              $user, $password);
          $dbh = DBI->connect("DBI:mysql:$database:$hostname:$port",
                              $user, $password);
     If the username and/or password are undefined, then the DBI will
     use the values of the `DBI_USER', `DBI_PASS' environment variables
     respectively. If you don't specify a hostname, then it will
     default to `"localhost"'. If you don't specify a port, then it
     defaults to the default mysql port (3306).

`prepare'
     Prepare gets a SQL statement ready for execution by the database
     engine and returns a statement handle `($sth)' which invokes the
     execute method. Example:
          $sth = $dbh->prepare($statement) or die "Can't prepare $statement:
          $dbh->errstr\n";

`do'
     The "do" method prepares and executes a SQL statement and returns
     the number of rows effected. This method is generally used for
     "non-select" statements which can not be prepared in advance
     (driver limitation) or which do not need to executed more than
     once (inserts, deletes, etc.). Examples:
          $rc = $dbh->do($statement) or
                  die "Can't execute $statement: $dbh- >errstr\n";

`disconnect'
     Disconnect will disconnect the database handle from the database.
     This is typically called right before you exit from the program.
     Example:
          $rc = $dbh->disconnect;

`quote'
     The quote method is used to "escape" any special characters
     contained in the string and to add the required outer quotation
     marks.
          $sql = $dbh->quote($string)

`execute'
     This method executes the prepared statement. For non-select
     satements, it returns the number of rows affected. For select
     statements, execute only starts the SQL query in the database. You
     need to use one of the `fetch_*' methods below to retrieve the
     data.  Example:
          $rv = $sth->execute or die "can't execute the query: $sth->errstr;

`fetchrow_array'
     This method "fetches" the next row of data and returns it as an
     array of field values.  Example:
          while(@row = $sth->fetchrow_array) {
                  print qw($row[0]\t$row[1]\t$row[2]\n);
          }

`fetchrow_arrayref'
     This method "fetches" the next row of data and returns it as a
     reference to an array of field values. Example:
          while($row_ref = $sth->fetchrow_arrayref) {
                  print qw($row_ref->[0]\t$row_ref->[1]\t$row_ref->[2]\n);
          }

`fetchrow_hashref'
     This method fetches a row of data and returns a reference to a hash
     table containing field name/value pairs. This method is not nearly
     as efficient as using array references as demonstrated above.
     Example:
          while($hash_ref = $sth->fetchrow_hashref) {
                  print qw($hash_ref->{firstname}\t$hash_ref->{lastname}\t\
                          $hash_ref- > title}\n);
          }

`fetchall_arrayref'
     This method is used to get all the data (rows) to be returned from
     the SQL statement. It returns a reference to an array of arrays of
     references to each row. You access/print the data by using a nested
     loop. Example:
          my $table = $sth->fetchall_arrayref or die "$sth->errstr\n";
          my($i, $j);
          for $i ( 0 .. $#{$table} ) {
                  for $j ( 0 .. $#{$table->[$i]} ) {
                          print "$table->[$i][$j]\t";
                  }
                  print "\n";
          }

`finish'
     Indicates that no more data will be fetched from this statement
     handle. You call this method to free up the statement handle and
     any system resources it may be holding.  Example:
          $rc = $sth->finish;

`rows'
     Returns the number of rows affected (updated, deleted, etc.) from
     the last command.  This is usually used after a do() or non-select
     execute() statement.
          $rv = $sth->rows;

`NULLABLE'
     A reference to an array of boolean values; TRUE indicates that this
     column may contain NULLs.
          $null_possible = $sth->{NULLABLE};

`NUM_OF_FIELDS'
     Number of fields returned by a SELECT or LISTFIELDS statement.
     You may use this for checking whether a statement returned a
     result: A zero value indicates a non-SELECT statement like INSERT,
     DELETE or UPDATE.
          $nr_of_fields = $sth->{NUM_OF_FIELDS};

`data_sources'
     This method returns an array of databases available to the mysql
     daemon on localhost.
          @dbs = DBI->data_sources("mysql");

`ChopBlanks'
     This determines whether a fetchrow will chop preceding and trailing
     blanks off the returned values.
          $sth->{'ChopBlanks') =1;

   *MySQL specific methods.*

`insertid'
     If you use the auto-increment feature of mysql, the new
     auto-incremented values will be stored here.
          $new_id = $sth->{insertid};

`is_blob'
     Reference to an array of boolean values; TRUE indicates that the
     respective column is a blob.
          $keys = $sth->{is_blob};

`is_key'
     Reference to an array of boolean values; TRUE indicates, that the
     respective column is a key.
          $keys = $sth->{is_key};

`is_num'
     Reference to an array of boolean values; TRUE indicates, that the
     respective column contains numeric values.
          $nums = $sth->{is_num};

`is_pri_key'
     Reference to an array of boolean values; TRUE indicates, that the
     respective column is a primary key.
          $pri_keys = $sth->{is_pri_key};

`is_not_null'
     A reference to an array of boolean values; FALSE indicates that
     this column may contain NULLs. You should better use the NULLABLE
     attribute above which is a DBI standard.
          $not_nulls = $sth->{is_not_null};

`max_length'
`length'
     A reference to an array of maximum column sizes. The max_length is
     the maximum physically present in the result table, length gives
     the theoretically possible maximum.
          $max_lengts = $sth->{max_length};
          $lengts = $sth->{length};

`NAME'
     A reference to an array of column names.
          $names = $sth->{NAME};

`table'
     Returns a reference to an array of table names.
          $tables = $sth->{table};

More DBI/DBD information
........................

   You can use the perldoc command to get more information about DBI.

     perldoc DBI
     perldoc DBI::FAQ
     perldoc mysql

   You can also use the `pod2man', `pod2html', etc.. tools to translate
to other formats.

   And of course you can find the latest DBI information at
http://www.hermetica.com/technologia/DBI/, the DBI web page
   And of course you can find the latest DBI information at
the DBI web
page t table, length gives      the theoretically possible maximum.

   .

   ement like INSERT,      DELETE or UPDATE.

   [$j]\t";                   }                   print "\n";
}

   amples: 6).

   port (http://www.hermetica.com/technologia/DBI/).

*MySQL* Java connectivity (JDBC)
================================

   Insert pointers/descriptions of JDBC.

*MySQL* PHP API's
=================

   PHP documentation (http://www.php.net/manual/ref.mysql.php3)

*MySQL* C++ API's
=================

   Insert pointers/descriptions for C++.

*MySQL* Python API's
====================

   Insert pointers/descriptions for Python.

*MySQL* TCL API's
=================

   Insert pointers/descriptions for TCL.

How does *MySQL* compare with other databases
*********************************************

How does *MySQL* compare with `mSQL'
====================================

   This section has been written by the *MySQL* developers so it should
be read with that in mind. But there are NO factual errors that we know
of.

   For a list of all supported limits, functions and types see the
crash-me web page (http://www.tcx.se/crash-me.html).

*Performance.*
     For a true comparison of speed see the growing *MySQL* benchmark
     suite. *Note Benchmarks::

     *MySQL* is significantly quicker on complex selects.

     `mSQL' can get patalogically slow if you chage the order of tables
     in a select. In the benchmark suite a time more that 15000 times
     slower than *MySQL* was seen.

     Because of no thread creation overhead, small parser, few features
     and simple security `mSQL' should be quicker at:

          Test that do a lot of connect/disconnect with a very simple
          query.  Inserts into very simple tables with few columns and
          keys.

        * `CREATE TABLE' and `DROP TABLE'.

        * `SELECT' one something that isn't an index. (A table scan is
          very easy)

     As these operations are so simple, it is hard to be better at them
     when you have a higher start overhead. After the connection is
     established *MySQL* should perform much better.

     *MySQL* on the other hand is much faster than `mSQL' and most
     other SQL implementions on the following:

          Retrieving large results (*MySQL* has a better, faster and
          safer protocol)

        * Tables with variable length strings since *MySQL* has more
          efficent handling and can have indexes on varchars.

        * Handling tables with many columns.

        * Handling tables with large record lengths.

        * SELECT with many expressions.

        * SELECT on large tables.

        * Handles many connections at the same time. *MySQL* is fully
          multi-threaded. Each connection has it is own thread, which
          means that none of them has to wait for the other (unless a
          query modifying the same table you need to use is executed).
          In `mSQL' all other connections have to wait until the first,
          doesn't matter whether the query is long or short, is
          executed and finished. After that the next connection can be
          served, while all the others wait again, etc.

        * Joins (We have seen (*Note Benchmarks::) speed differences of
          17000 times on this one). This is because mSQL doesn't have a
          join optimizer that orders tables in the optimal order. If
          one however put the tables in exactly the right order in mSQL
          2 the join will be relatively fast!

        * `ORDER BY' and `GROUP BY'.

        * `DISTINCT'.

        * Using `TEXT' or `BLOB' columns.

*SQL Features*
       1. `GROUP BY' & `HAVING' *MySQL* supports a full `GROUP BY' with
          both `HAVING' and the following functions `count()', `avg()',
          `min()', `max()', `sum()' and `std()'. `min()' and `max()'
          may take string arguments. `count(*)' is optimised to return
          very quickly if this is the only thing in the query. `mSQL'
          does not support `GROUP BY' at all.

       2. `INSERT' & `UPDATE' with calculations.  *MySQL* can do
          calculations in a `INSERT' or `UPDATE'.
               UPDATE SET x=x*10+y WHERE x<20;

       3. Aliasing *MySQL* has column aliasing.

       4. Qualifying column names.  If a column name is unique you do
          not have to use the full qualifier.

       5. `SELECT' with functions *MySQL* has too many functions to
          list here. *Note Functions::.


*Disk space efficiency*
     That is, how small can you make your tables.

     *MySQL* has very precise types so that use can create tables that
     take very little space. An example of a useful *MySQL* datatype is
     the mediumint that is 3 bytes long. If you have 10.000.0000
     records even saving one byte per record is very important.

     Since `mSQL2' only has 4 types (char,text,int,real) it is hard to
     get small tables.

*Stability*
     This is harder to judge objectively. For *MySQL* stability see
     *Note Stability::.

     We have no experience with `mSQL' stability so we can not say
     anything about that.

*Price*
     Another important issue is of course the license. *MySQL* has a
     more flexible license than `mSQL' and is also cheaper than `mSQL'.
     Remember to at least consider paying for a license or email
     support for whatever product you choose to use. If you sell a
     product with *MySQL* you are of course required to get a license
     for this.

*Perl interfaces*
     *MySQL* has basically the same interfaces to perl as `mSQL' with
     some added features.

*JDBC (Java)*
     *MySQL* has a Java interface by GWE technologies that has been
     improved by Xiaokun Kelvin ZHU.

     We know that `mSQL' has one but we have too little experience with
     it to compare.

*Rate of development*
     *MySQL* has a very small team of developers, but we are quite used
     to coding C and C++ very rapidly. Since threads, functions, group
     by and so on are still not implemented in `mSQL', it has a lot of
     catching up to do. To get some perspective on this you can view
     the `mSQL' HISTORY file for the last year and compare it with the
     News section. *Note News::. It should be pretty obvious which one
     has developed most rapidly.

*Utility programs*
     Both `mSQL' and *MySQL* have a lot of interesting third-party
     tools. Since it is very easy to port upwars (`mSQL' -> *MySQL*)
     *MySQL* has almost all interesting `mSQL' applications.

     *MySQL* comes with a simple msql2mysql program that fixes the
     different spelling of the most used functions. A conversion of a
     client program from `mSQL' to mySQL usually takes a couple of
     minutes.

How about `mSQL' tools like msql-tcl, msqljava?
-----------------------------------------------

   According to our experience it would just take a few hours to
convert a tool using the `mSQL' C API to the *MySQL* C API.

   The procedure:

  1. Run the shell script msql2mysql on the source. This needs the
     binary program replace, which is distributed with *MySQL*.

  2. Compile

  3. Fix all compiler errors:

   Differences between the *MySQL* and `mSQL' C API's.
   * *MySQL* uses *MySQL* as a connection type (`mSQL' uses an `int').

   * *MySQL* connect takes a pointer to a MYSQL structure as a
     parameter.  It is easy to define one globally or use malloc to get
     one.

   * mysql_connect takes 2 extra parameters. You may set these to
     NULL,NULL for default use (user and password).

   * mysql_error takes the MYSQL structure as a parameter. Just add the
     parameter to your old msql_error code if you are porting old code.

   * Some incompatibilities exist as a result of *MySQL* supporting
     multiple connections to the server from the same process.

   * *MySQL* returns an error number and a text for all errors. `mSQL'
     only returns a text error

How different from `mSQL' are the *MySQL* client/server communications protocols?
---------------------------------------------------------------------------------

   There are enough differences that it is impossible (at least not
easy) to support both.

   The greatest differences between *MySQL* and `mSQL' are:

   * A message buffer may contain many result rows.

   * The message buffers are dynamically enlarged if the question or the
     result is bigger than the current buffer up to a configurable
     server and client limit.

   * All packages are numbered to catch duplicated or missing packets.

   * All columns are sent in ASCII, the length of columns and rows are
     sent in packed binary coding (1,2 or 3 bytes).

   * *MySQL* can read in the result unbuffered (without having to store
     the full set in the client).

   * If a single write/read takes more than 30 seconds then the server
     closes the connection.

   * If nothing has happened on a connection for 8 hours the server
     closes the connection.

What are the differences in the SQL syntax between *MySQL* & `mSQL' 2.0?
------------------------------------------------------------------------

   * `CREATE TABLE'

    `*MySQL*'
          Has (among others) the following extra types: *Note Create
          table::
             - `UNSIGNED' option for all integer columns.

             - `ZEROFILL' option for all integer columns.

             - `AUTO_INCREMENT' option for all integer columns that
               also is a `PRIMARY KEY'. *Note mysql_insert_id::.

             - `DEFAULT' value for all columns.

             - `ENUM' type for one of a set of strings.

             - `SET' type for many of a set of string.

             - `BIGINT' type for 64 bit integers.

    `mSQL2'
          `mSQL' type         Corresponding *MySQL* type.                 
          char(len)           char(len)                                   
          text(len)           text(len). len is the maximal length. And   
                              `LIKE' works.                               
          int                 int. With many more options!                
          real                real. Or float. Both 4 and 8 bytes          
                              versions are available.                     
          uint                Unsigned integer.                           
          date                date. Takes ANSI SQL format instead of      
                              `mSQL's own.                                
          time                time                                        
          money               decimal(12,2). A fixed point value with     
                              two decimals.                               

   * To create indexes.
    `*MySQL*'
          All indexes have to be given to `CREATE TABLE'. Indexes can
          not be removed without recreating the table. *Note Alter
          table::.

    `mSQL'
          Indexes must be created by a separate `CREATE INDEX' clause.
          Indexes may be removed with `DROP INDEX'.

   * To get a unique identifier in a table at insert.
    `*MySQL*'
          Use `AUTO_INCREMENT' as a column type specifier. *Note
          mysql_insert_id::.

    `mSQL'
          Create a `SEQUENCE' on a table and select the `_seq' column.

   * To get a unique identifier for a row.
    `*MySQL*'
          Add a `PRIMARY KEY' to the table.

    `mSQL'
          Use the `_rowid' column. Observe that `_rowid' may change
          depending on many factors.

   * To get the time a column was last modified.
    `*MySQL*'
          Add a `TIMESTAMP' column to the table. This column will
          automatically be updated to the current time if you don't
          give the column a value or if you give it a NULL value in a
          `UPDATE' or `INSERT' statement.

    `mSQL'
          Use the `_timestamp' column.

   * In mSQL NULL = NULL is TRUE.  *MySQL* follows ANSI SQL and a
     comparison with NULL is always NULL.  One has to change `=NULL' to
     `IS NULL' when porting old code from mSQL to *MySQL*.

   * All string comparisons are by default case independent with case
     according to ISO-8859-1 Latin1.  If you don't like this you should
     declare your columns with the `BINARY' attribute.

   * Case insensitive searching.
    `*MySQL*'
          `LIKE' is case insensitive or case sensitive depending on the
          used columns. If possible *MySQL* uses indexes if the like
          argument doesn't start with a wildcard.

    `mSQL'
          Use `CLIKE'.

   * End space handling.
    `*MySQL*'
          Stripps all spaces att the end of `CHAR' and `VARCHAR'
          columns. Currently use a `TEXT' column if this behavior is
          undesired.

    `mSQL'
          Keeps end space.

   * What are the differences in the `WHERE' statement?
    `*MySQL*'
          *MySQL* does everything correctly prioritized (AND is
          evaluated before OR). To get `mSQL' behaviour in *MySQL*, use
          parenthesis: `select * from table where a=1 and b=2 or a=3
          and b=4' -> `select * from table where (a=1 and (b=2 or (a=3
          and (b=4))))'.

    `mSQL'
          Evaluates everything from left to right. That means that some
          logical calculations with more that 3 arguments can not be
          expressed in any way. This also mean that you have to change
          some queries when you upgrade to *MySQL*. You do this easy by
          adding parenthesis.

          Always when you are in doubt about what a query does:

            1. Remove all distinct keywords to make the query easier to
               debug.

            2. Write all columns from all tables to really see what you
               are doing.

          This will make it easier to see what goes wrong.

   * Access Control
    `*MySQL*'
          Has tables to store grant options per user, host and db.
          *Note Privileges::

    `mSQL'
          Has a file `mSQL.acl' where you can grant read/write
          privileges for users.

    `'
How does *MySQL* compare with PostgreSQL
========================================

   For a list of all supported limits, functions and types see the
crash-me web page (http://www.tcx.se/crash-me.html).

   PostgreSQL has some more advanced features like user-defined types,
triggers, rules and transactions. But it lacks a lot of the standard
types and functions from ANSI SQL and ODBC. See the
crash-me web page (http://www.tcx.se/crash-me.html) for a complete list
of supported/unsupported types/function.

   Normally PostgreSQL is much slower than *MySQL*. *Note Benchmarks::.

Some users of *MySQL*.
**********************

   * Some Web search engines:
        - AAA Matilda Web Search (http://www.aaa.com.au)

        - What's New (http://www.whatsnu.com/)

        - Aladin (http://www.aladin.de/)

        - Columbus Finder (http://www.columbus-finder.de/)

        - Spider (http://www.spider.de/)

        - Blitzsuche (http://www.blitzsuche.de/)

        - Indoseek Indonesia (http://www.indoseek.co.id)

        - Yaboo - Yet Another BOOkmarker (http://www.yaboo.dk/)

   * Some Domain/Internet/Web and related services:
        - Registry over Web providers           who supports *MySQL* (http://www.wix.com/mysql-hosting)

        - Monolith Internet Services (http://www.ml.org) runs *MySQL*
          supporting nearly a million rows and over 100,000 users.

        - Online Database (http://worldcommunity.com/ffwpu)

        - BigBiz Internet Services (http://www.bigbiz.com)

        - Fotball (Soccer) search page (http://www.soccersearch.com)

        - The Virt Gazette (http://virt.circle.net)

   * Not categorized pages:
        - Internet information server (http://online.dn.ru)

        - AZC.COM's Feature Showcase (http://www.feature-showcase.com/htmls/demo_mysql.sql)

        - The Music Database (http://www.musicdatabase.com/)

        - Musical note-sheets (http://www.kiss.de/musik-mueller)

        - Bagism a John Lennon fan page (http://www.bagism.com)

        - Musician's           looking for other musicians (Free Service) (http://TheMatrix.com/~matrix/band_search.phtml)

        - Course Search (http://www.teach.org.uk/subjects/trainingcourse/g.html)

        - Northerbys Online Auctions (http://www.northerbys.com)

        - Amsterdam Airport           Schiphol (http://www.schiphol.nl/flights/home.htm)

        - CD database (http://TheMatrix.com/seventhsin/query.phtml)

        - Used Audio Gear Database
          (http://TheMatrix.com/~flmm/GEAR.html)

        - US Folk art broker (http://www.selftaught.com/)

        - Mail reading on the web (http://organizer.net/)

        - Free home pages on           www.somecoolname.mypage.org (http://www.mypage.org/)

        - Der Server fr Schulen im Web (In           German) (http://www.schulweb.de/)

        - Auldhaefen Online Services (http://www.ald.net/)

        - CaryNET Information Center (http://www.cary.net/)

        - Dataden Computer Systems (http://www.dataden.com/)

        - Andremuseet (In Swedish) (http://andree.grm.se/)

        - HOMESITE Internet Marketing (http://www.him.net/)

        - Jade-V Network Services  (http://www.jade-v.com/techinfo.html)

        - http://ww2010.atmos.uiuc.edu/(Gl)/abt/aknw/tech.rxml, Weather
          World 2010 Technical Credits
        - Weather           World 2010 Technical Credits arch.phtml)

          0,000 users.

          d types and functions from ANSI SQL and ODBC. See the
          crash-me web page (http://www.tcx.se/crash-me.html) for a
          complete list of supported/unsupported types/function.

          thesis.

          the last year and compare it with the      News section.
          *Note News::. It should be pretty obvious which one      has
          developed most rapidly.

          t the next connection can be           served, while all the
          others wait again, etc.

          ther queries while using `mysql_use_result'.

          s root, as a user or as anyone else. The access permissions
          and userbase of *MySQL* are completely separate from the UNIX
          users. The only connection to the UNIX users is if you don't
          use the -u option to clients. In this case the client will
          try to login into *MySQL* with your UNIX login name. If your
          UNIX box itself isn't secured, you should probably at least
          put a password on the root users in the *MySQL* access
          tables, since any johndoe user can run 'mysql -u root dbname'
          and do whatever he likes.

          1     1      2     2     4      3     6     4      4     10
          1      5     11    20      6     31    1      7     32    30
              8     62    35      9     97    35      10    132   35
            11    167   4      12    171   16      13    187   35
          14    222   4      15    226   16      16    242   20      17
            262   20      18    282   20      19    302   30      20
          332   4      21    336   4      22    340   1      23    341
           8      24    349   8      25    357   8      26    365   2
             27    367   2      28    369   4      29    373   4
          30    377   1      31    378   2      32    380   8      33
          388   4      34    392   4      35    396   4      36    400
           4      37    404   1      38    405   4      39    409   4
             40    413   4      41    417   4      42    421   4
          43    425   4      44    429   20      45    449   30      46
            479   1      47    480   1      48    481   79      49
          560   79      50    639   79      51    718   79      52
          797   8      53    805   1      54    806   1      55    807
          20      56    827   4      57    831   4
          Compressing station.ISD: (1192 records)      - Calculating
          statistics            normal:     20  empty-space:      16
          empty-zero:        12  empty-fill:  11      pre-space:   0
          end-space:        12  intervall-fields:   5  zero:         7
             Original trees:  57  After join: 17      - Compressing
          file      87.14%            (/my/monty/tmp) ls -l station.*
            -rw-rw-r--   1 monty    my         127874 Apr 17 19:00
          station.ISD      -rw-rw-r--   1 monty    my          55296
          Apr 17 19:04 station.ISM      -rw-rw-r--   1 monty    my
              5767 Apr 17 19:00 station.frm            (my/monty/tmp)
          isamchk -dvv station            ISAM file:     station
          Isam-version:  2      Creation time: 1996-03-13 10:08:58
          Recover time:  1997-04-17 19:04:26      Data records:
              1192  Deleted blocks:              0      Datafile:
          Parts:           1192  Deleted data:                0
          Datafilepointer (bytes):      3  Keyfile pointer (bytes):
          1      Max datafile length:   16777215  Max keyfile length:
           131071      Recordlength:               834      Record
          format: Compressed            table description:      Key
          Start Len Index   Type                       Root  Blocksize
           Rec/key      1   2     4   unique  unsigned long
          10240       1024          1      2   32    30  multip. text
                             54272       1024          1
          Field Start Length Type                         Huff tree
          Bits      1     1     1      constant
             1     0      2     2     4      zerofill(1)
                    2     9      3     6     4      no zeros,
          zerofill(1)                2     9      4     10    1
                                           3     9      5     11    20
             table-lockup                         4     0      6
          31    1                                           3     9
          7     32    30     no endspace, not_always              5
          9      8     62    35     no endspace, not_always, no empty
           6     9      9     97    35     no empty
                  7     9      10    132   35     no endspace,
          not_always, no empty    6     9      11    167   4
          zerofill(1)                          2     9      12    171
          16     no endspace, not_always, no empty    5     9      13
          187   35     no endspace, not_always, no empty    6     9
           14    222   4      zerofill(1)                          2
           9      15    226   16     no endspace, not_always, no empty
            5     9      16    242   20     no endspace, not_always
                   8     9      17    262   20     no endspace, no
          empty                8     9      18    282   20     no
          endspace, no empty                5     9      19    302   30
             no endspace, no empty                6     9      20
          332   4      allways zero                         2     9
          21    336   4      allways zero                         2
          9      22    340   1
           3     9      23    341   8      table-lockup
                  9     0      24    349   8      table-lockup
                        10     0      25    357   8      allways zero
                                2     9      26    365   2
                                       2     9      27    367   2
          no zeros, zerofill(1)                2     9      28    369
          4      no zeros, zerofill(1)                2     9      29
          373   4      table-lockup                        11     0
           30    377   1                                           3
           9      31    378   2      no zeros, zerofill(1)
            2     9      32    380   8      no zeros
                   2     9      33    388   4      allways zero
                          2     9      34    392   4      table-lockup
                                12     0      35    396   4      no
          zeros, zerofill(1)               13     9      36    400   4
             no zeros, zerofill(1)                2     9      37
          404   1                                           2     9
          38    405   4      no zeros                             2
          9      39    409   4      allways zero
           2     9      40    413   4      no zeros
                  2     9      41    417   4      allways zero
                         2     9      42    421   4      no zeros
                                2     9      43    425   4
          allways zero                         2     9      44    429
          20     no empty                             3     9      45
          449   30     no empty                             3     9
           46    479   1                                          14
           4      47    480   1
           14     4      48    481   79     no endspace, no empty
                  15     9      49    560   79     no empty
                          2     9      50    639   79     no empty
                                 2     9      51    718   79     no
          endspace                         16     9      52    797   8
             no empty                             2     9      53
          805   1                                          17     1
          54    806   1                                           3
          9      55    807   20     no empty
           3     9      56    827   4      no zeros, zerofill(2)
                  2     9      57    831   4      no zeros,
          zerofill(1)                2     9

          Rec/k (http://ww2010.atmos.uiuc.edu/(Gl)/abt/aknw/tech.rxml)

        - About The Gimp plugin           registry (http://gimp.foebud.org/registry/doc/)

        - Java           tool Archiver technical detail (Slightly optimistic about           *MySQL* ANSI-92 complicate)2* (http://www.fast-inc.com/Products/Archiver/database.html)

        - Games Domain           Cheats Database (http://www.gamesdomain.com/cheats/usrcheat.phtml)

        - The "Powered By" Page           (Kcilink) (http://www.kcilink.com/poweredby/)

        - Netcasting (http://www.netcasting.net/index.whtml)

        - http://homepages.tig.com.au/~mjj/nbltips, NBL (Australian
          National Basketball League) tipping
        - NBL (Australian           National Basketball League) tipping
          icate)2*
          (http://www.fast-inc.com/Products/Archiver/database.html)

          7    35      10    132   35             11    167   4      12
            171   16      13    187   35           14    222   4
          15    226   16      16    242   20      17             262
          20      18    282   20      19    302   30      20
          332   4      21    336   4      22    340   1      23    341
                   8      24    349   8      25    357   8      26
          365   2              27    367   2      28    369   4      29
            373   4           30    377   1      31    378   2      32
            380   8      33           388   4      34    392   4
          35    396   4      36    400            4      37    404   1
             38    405   4      39    409   4              40    413
          4      41    417   4      42    421   4           43    425
          4      44    429   20      45    449   30      46
          479   1      47    480   1      48    481   79      49
            560   79      50    639   79      51    718   79      52
                 797   8      53    805   1      54    806   1      55
            807           20      56    827   4      57    831   4
               Compressing station.ISD: (1192 records)      -
          Calculating           statistics            normal:     20
          empty-space:      16           empty-zero:        12
          empty-fill:  11      pre-space:   0           end-space:
           12  intervall-fields:   5  zero:         7
          Original trees:  57  After join: 17      - Compressing
            file      87.14%            (/my/monty/tmp) ls -l station.*
                     -rw-rw-r--   1 monty    my         127874 Apr 17
          19:00           station.ISD      -rw-rw-r--   1 monty    my
                55296           Apr 17 19:04 station.ISM
          -rw-rw-r--   1 monty    my               5767 Apr 17 19:00
          station.frm            (my/monty/tmp)           isamchk -dvv
          station            ISAM file:     station
          Isam-version:  2      Creation time: 1996-03-13 10:08:58
              Recover time:  1997-04-17 19:04:26      Data records:
                    1192  Deleted blocks:              0      Datafile:
                   Parts:           1192  Deleted data:
          0           Datafilepointer (bytes):      3  Keyfile pointer
          (bytes):           1      Max datafile length:   16777215
          Max keyfile length:            131071      Recordlength:
                  834      Record           format: Compressed
            table description:      Key           Start Len Index
          Type                       Root  Blocksize            Rec/key
              1   2     4   unique  unsigned long           10240
          1024          1      2   32    30  multip. text
                         54272       1024          1           Field
          Start Length Type                         Huff tree
          Bits      1     1     1      constant              1     0
           2     2     4      zerofill(1)                     2     9
             3     6     4      no zeros,           zerofill(1)
                 2     9      4     10    1
                         3     9      5     11    20
          table-lockup                         4     0      6
          31    1                                           3     9
               7     32    30     no endspace, not_always
          5           9      8     62    35     no endspace,
          not_always, no empty            6     9      9     97    35
           no empty                   7     9      10    132   35
          no endspace,           not_always, no empty    6     9
          11    167   4           zerofill(1)
          2     9      12    171           16     no endspace,
          not_always, no empty    5     9      13           187   35
          no endspace, not_always, no empty    6     9            14
          222   4      zerofill(1)                          2
           9      15    226   16     no endspace, not_always, no empty
                     5     9      16    242   20     no endspace,
          not_always                    8     9      17    262   20
          no endspace, no           empty                8     9
          18    282   20     no           endspace, no empty
             5     9      19    302   30              no endspace, no
          empty                6     9      20           332   4
          allways zero                         2     9           21
          336   4      allways zero                         2
          9      22    340   1            3     9      23    341   8
           table-lockup                   9     0      24    349   8
            table-lockup                         10     0      25
          357   8      allways zero                                 2
           9      26    365   2
          2     9      27    367   2           no zeros, zerofill(1)
                     2     9      28    369           4      no zeros,
          zerofill(1)                2     9      29           373   4
             table-lockup                        11     0
          30    377   1                                           3
                9      31    378   2      no zeros, zerofill(1)
              2     9      32    380   8      no zeros
            2     9      33    388   4      allways zero
                     2     9      34    392   4      table-lockup
                                    12     0      35    396   4      no
                   zeros, zerofill(1)               13     9      36
          400   4              no zeros, zerofill(1)                2
            9      37           404   1
                    2     9           38    405   4      no zeros
                                2           9      39    409   4
          allways zero            2     9      40    413   4      no
          zeros                   2     9      41    417   4
          allways zero                          2     9      42    421
          4      no zeros                                 2     9
          43    425   4           allways zero
          2     9      44    429           20     no empty
                        3     9      45           449   30     no
          empty                             3     9            46
          479   1                                          14
          4      47    480   1            14     4      48    481   79
             no endspace, no empty                   15     9      49
           560   79     no empty                           2     9
          50    639   79     no empty
          2     9      51    718   79     no           endspace
                         16     9      52    797   8              no
          empty                             2     9      53
          805   1                                          17     1
               54    806   1
          3           9      55    807   20     no empty            3
           9      56    827   4      no zeros, zerofill(2)
               2     9      57    831   4      no zeros,
          zerofill(1)                2     9

          49    560   79     no empty                             2
          9      50    639   79     no empty
          2     9      51    718   79     no endspace
                16     9      52    797   8      no empty
                        2     9      53    805   1
                              17     1      54    806   1
                                      3     9      55    807   20
          no empty                             3     9      56    827
          4      no zeros, zerofill(2)                2     9      57
          831   4      no zeros, zerofill(1)                2     9

          Rec/k (http://homepages.tig.com.au/~mjj/nbltips)

        - CGI shop (http://www.cgishop.com/)

        - Whirlycott: Website Design (http://www.whirlycott.com/)

        - Museum Tusculanum Press (http://www.mtp.dk)

        - Centro Siciliano di           Documentazione (http://csdgi.historie.ku.dk/biblio)

        - Quake statistics database (http://caribou.dyn.ml.org:8000)

        - OpenDebate - Interactive Polls &           Open Discussion (http://www.opendebate.com)

        - Online           chemical dissertation server (http://vermeer.organik.uni-erlangen.de/dissertationen/)

        - FreSch! The Free Scholarship Search           Service (http://www.freschinfo.com)

        - Stockholm Pinball           Locator (http://www.nada.kth.se/~staffanu/pinball)

        - HEK A construction company (http://www.hek.com)

        - Elsevier Bussines Information (http://www.nbi.nl)

        - Medicial Links (Using           Coldfusion and MySQL) (http://vaccination.medicallink.se/)

        - Search for jobs & people at           JobLink-USA (http://www.joblink-usa.com)

        - Daily news about Linux           in German language (http://www.linux-magazin.de/newsflash/)

        - Competition Formation           Skydiving (http://www.skydive.net/competfs)

        - E-commerce and internal accounting (http://www.galaxy-net.net/Galaxy-NET Telecommunications)

        - Denmarks leading business daily           newspaper Brsen (http://www.borsen.dk/)

        - The Internet NES Database (http://tmmm.simplenet.com/indb/)

        - Travel agency in Prague in 3 languages (http://www.russia.cz)

        - Linkstation (http://www.linkstation.de)

        - Searchable online database at           Peoplestaff (http://www.peoplestaff.com)

   * Some MySQL consultants
        - Ayni AG (http://www.ayni.com)

   Send any additions to this list to <webmaster@tcx.se>.

Contributed programs
********************

   Many users of *MySQL* has contributed *very* useful support tools
and addons.

   Here is a list of what is available at `http://www.tcx.se/Contrib'
(Or any mirror).

`Db.py'
     Python module with caching. By <gandalf@rosmail.com>.

`Old-Versions'
     Previous versions of things found here that you probably wont be
     interested in.

`00-README'
     This listing.

`Vdb-dflts-2.1.tgz'
     This is a new version of a set of library utilities whose
     intention is to provide a generic interface to SQL database
     engines such that your application becomes a 3 tiered application.
     The advantage is that you can easily switch between and move to
     other database engines by implementing one file for the new
     backend without needing to make any changes to your applications.
     By <damian@cablenet.net>.

`access_to_mysql.txt'
     Paste this function into an Access module of a database which has
     the tables you want to export. See also exportsql. By Brian
     Andrews.

`dbf2mysql-1.10d.tar.gz'
     Convert between .dbf files and *MySQL* tables.
     By Maarten Boekhold <boekhold@cindy.et.tudelft.nl> and Michael
     Widenius.

`delphi-interface.gz'
     Delphi interface to libmysql.dll, by Blestan Tabakov.
     <root@tdg.bis.bg>

`dump2h-1.00.gz'
     Converter from a mysqldump output to a C header file. By Harry
     Brueckner <brueckner@mail.respublica.de>

`emacs-sql-mode.tar.gz'
     Raw port of a SQL mode for XEmacs. Supports completion. Original by
     Peter D. Pezaris <pez@atlantic2.sbi.com> and *MySQL* port by David
     Axmark

`exportsql.txt'
     A script that is similar to the "access_to_mysql.txt". Only this
     one is fully configurable, has better type conversion (including
     detection of TIMESTAMP fields), gives out warnings and suggestions
     while converting, quotes *all* special characters on text and
     binary data, and so on. And it will also convert to mSQL v1 and
     v2, and is free of charge for anyone. See
     `http://www.cynergi.net/prod/exportsql/' for latest version. By
     Pedro Freire <support@cynergi.net>

`findres.pl'
     Find reserved words in tables. By Nem W Schlecht.

`handicap.tar.gz'
     Performance handicapping system for yachts. Uses PHP. By
     <rhill@stobyn.ml.org>

`hylalog-1.0.tgz'
     Store hylafax outgoing faxes in *MySQL* database. By Sinisa
     Milivojevic <sinisa@coresinc.com>

`importsql.txt'
     A script that does the exact reverse of 'exportsql.txt'.  That is,
     it imports data from *MySQL* into an Access database via ODBC. This
     is very handy when combined with exportSQL, since it lets you use
     Access for all DB design and administration, and synchronize with
     your actual *MySQL* server either way. Free of charge. See
     `http://www.netdive.com/freebies/importsql/' for any updates.
     Created by Laurent Bossavit of NetDIVE.

`jms130b.zip'
     JDBC driver for *MySQL*. Also contains command line client and
     other examples. By Xiaokun Kelvin ZHU and GWE Technologies

`twz1jdbcForMysql-0.7.11-beta.tar.gz'
     New JDBC driver for *MySQL*. This is a beta release and is
     actively developed. By Terrence W. Zellers.  <zellert@voicenet.com>
     You can always find the newest driver at
     `http://www.voicenet.com/~zellert/tjFM'

`mod_auth_mysql-2.11.tar.gz'
     Apache authentication module for *MySQL*. By Zeev Suraski
     <bourbon@netvision.net.il>

`mod_log_mysql-1.05.tar.gz'
     *MySQL* logging module for Apache. By Zeev Suraski
     <bourbon@netvision.net.il>

`mrtg-mysql-1.0.tar.gz'
     *MySQL* status plotting with MRTG, by Luuk de Boer <luuk@wxs.nl>.

`msqltcl-1.50.tar.gz'
     Tcl interface for msql. See also mysqltcl.c-patch. By Hakan
     Soderstrom,

`mysqltcl.c-patch'
     Patch for msqltcl-1.50.tar.gz.

`mysqltcl-1.53.tar.gz'
     Tcl interface for mysql. Based on msqltcl-1.50.tar.gz.  Updated by
     Tobias Ritzau <tobri@ida.liu.se> <hs@soderstrom.se>

`MySQLmodule-1.1.tar.gz'
     Pyton interface for *MySQL*. By Joseph Skinner
     (<joe@earthlight.co.nz>)

`mypasswd-2.0.tgz'
     Extra for mod_auth_mysql. This is a little tool which allows to
     add/change user records storing group and/or password entries in
     *MySQL* tables. By Harry Brueckner <brueckner@respublica.de>

`mysql-c++-0.02.tar.gz'
     *MySQL* C++ wrapper library. By Roland Haenel <rh@ginster.net>

`http://sunsite.unc.edu/kevina/mysql++/'
     *MySQL* C++ API; More than just a wrapper library.  By
     <kevina@clark.net>

`mysql-passwd.README'
`mysql-passwd-1.2.tar.gz'
     Extra for mod_auth_mysql. This is a two part system for use with
     mod_auth_mysql.

`mysql_watchdog.pl'
     Monitor *MySQL* Daemon for possible lockups. By Yermo Lamers
     <yml@yml.com>

`mysql-webadmin-1.0a8-rz.tar.gz'
     A tool written in PHP-FI to administrate *MySQL* databases
     remotely over the web within a Web-Browser. By Peter Kuppelwieser
     <peter.kuppelwieser@kantea.it>. Updated by Wim Bonis
     <bonis@kiss.de>

`mysqladm.tar.gz'
     *MySQL* Web Database Administration written in perl.  By Tim
     Sailer.

`mysqladm-2.tgz'
     Updated version of mysqladm.tar.gz, by High Tide.

`nsapi_auth_mysql.tar'
     Netscape Web Server API (NSAPI) functions to authenticate (BASIC)
     users against *MySQL* tables. By Yuan John Jiang

`mysqlwinadmn.zip'
     Win32 GUI (binary only) to administrate a database, by David B.
     Mansel.  <david@zhadum.org>

`pam_mysql.tgz'
     This module authenticate user via a pam , using mysql.

`pike-mysql-1.4.tar.gz'
     *MySQL* module for pike. For use with the Roxen web server.

`radius-0.3.tar.gz'
     Patches for radiusd to make it support *MySQL*. By Wim Bonis
     <bonis@kiss.de>

`sqlscreens-0.3.2.tar.gz'
     TCL/TK code to generate database screens. By Jean-Francois Dockes.

`squile.tar.gz'
     Module for guile that allows guile to interact with sql databases.
     By Hal Roberts.

`twz1jdbcForMysql-0.7.11-beta.tar.gz'
     New java JDBC driver, by Terrence W. Zellers <zellert@uscom.com>

`mm.mysql.jdbc-0.6.tar.gz'
     Another new java JDBC driver, by Mark Matthews
     <mmatthew@ecn.purdue.edu>

`wmtcl.doc'
`wmtcl.lex'
     With this you can write html files with inclusions of TCL code. By
     <vvs@scil.npi.msu.su>

`wuftpd-2.4.2b12+mysql_support.tar.gz'
     Pacthes to add logging to *MySQL* for WU-ftpd. By Zeev Suraski
     <bourbon@netvision.net.il>

`www-sql-0.5.1.lsm'
`www-sql-0.5.1.md5'
`www-sql-0.5.1.tar.gz'
     A CGI program that parses an HTML file containing special tags,
     parses them and inserts data from a *MySQL* database.

`xmysql-1.8.tar.gz'
     A front end to the *MySQL* database engine. It allows for simple
     queries and table maintenance, as well as batch queries. By Rick
     Mehalick <dblhack@wt.net>

`xmysqladmin-0.4.4.tar.gz'
     A front end to the *MySQL* database engine.  It allows reloads,
     status check, process control, isamcheck, grant/revoke privileges,
     creating databases, drop databases, create, alter, browse and drop
     tables.  By Gilbert Therrien <gilbert@ican.net>

Who has helped to make *MySQL*.
*******************************

   Contributors to the *MySQL* distribution in somewhat random order:

Michael (Monty) Widenius
     Has written the following parts of *MySQL*:
        * All the main code in `mysqld'.

        * New functions for the string library.

        * Most of the mysys library.

        * The `NISAM' library (A B-tree index file handler with index
          compression and different record formats).

        * The heap library. A memory table system with our superior
          full dynamic hashing. In use since 1981 and published around
          1984.

        * replace (Look into it, it's COOL!).

        * myodbc, the ODBC driver for Windows95.

        * Fixing bugs in MIT-pthreads to get it to work for *MySQL*. And
          also UNIREG A curses based application tool with lot of
          utilities.

        * Porting of `mSQL' tools like msqlperl, DBD/DBI and DB2mysql.

David Axmark
        * Coordinator and main writer for the *Reference Manual*
          including enhancements to `texi2html'. Also automatic website
          updating from this manual.

        * autoconf & automake support.

        * The licensing stuff.

        * Parts of all the text files. Now days only the `README' is
          left. The rest ended up in the manual.

        * Our Mail master.

        * Lots of testing of new features.

        * Our in house 'free' software lawyer.

        * Mailing list maintainer (who never has the time to do it
          right...)

        * Our original portability code (more than 10 years old now).
          Now days only some parts of mysys are left.

        * Someone for Monty to call in the middle of the night when he
          just got that new feature to work :-)

Kim Aldale
     Rewriting Monty's and David's attempts at English into English.

Allan Larsson (The BOSS at TcX)
     For all the time he has allowed Monty to spend on this 'maybe
     useful' tool (*MySQL*). Dedicated user (and bug finder) of UNIREG
     & *MySQL*.

Per Eric Olsson
     For more or less constructive criticism and real testing of the
     dynamic record format.

David J. Hughes
     For the effort to make a shareware SQL database. We at TcX started
     with mSQL but found that it couldn't satisfy our purposes so
     instead we wrote a SQL interface to our application builder
     UNIREG.  mysqladmin & mysql are programs that were largely
     influenced by their mSQL counterparts. We have put a lot of effort
     into making the *MySQL* syntax a superset of mSQL. Much of the
     API:s ideas are borrowed from mSQL to make it easy to port free
     mSQL programs to *MySQL*. *MySQL* doesn't contain any code from
     mSQL. Two files (`client/insert_test.c' and
     `client/select_test.c') in the distribution are non copyrighted
     files from the mSQL distribution (Copyrighted David J. Hughes).
     These are included as a example of the changes that must be done
     to change from mSQL to *MySQL*.

Fred Fish
     For his excellent C debugging and trace library. Monty has made a
     number of smaller improvements to the library (speed and
     additional options).

Richard A. O'Keefe
     For his public domain string library.

Henry Spencer
     For his regex library, used in 'WHERE column REGEXP regexp'.

Free Software Foundation
     From whom we got an excellent compiler (gcc) and for their libc
     from which I have borrowed strto.c to get some code working in
     Linux. Also readline for the client.

Free Software Foundation & The XEmacs development team
     For a really great editor/environment used by almost everybody at
     tcx/detron.

Igor Romanenko (igor@frog.kiev.ua)
     mysqldump  (Previously msqldump but ported and enhanced by Monty)

Tim Bunce, Alligator Descartes
     For the DBD (perl) interface.

Andreas Koenig <a.koenig@mind.de>
     For the perl interface to *MySQL*

Eugene Chan <eugene@acenet.com.sg>
     For porting PHP to *MySQL*.

Michael J. Miller Jr. <mke@terrapin.turbolift.com>
     For the growing *MySQL* user manual. And a lot of
     spelling/language fixes for the FAQ.

Giovanni Maruzzelli <maruzz@matrice.it>
     For porting iODBC (unix ODBC).

Chris Provenzano
     Portable user level pthreads. From the copyright: This product
     includes software developed by Chris Provenzano, the University of
     California, Berkeley, and contributors.  We are currently using
     version 1_60_beta6 patched by Monty (see
     mit-pthreads/Changes-mysql).

Xavier Leroy <Xavier.Leroy@inria.fr>
     The author of LinuxThreads (used by *MySQL* on Linux).

Zarko Mocnik <zarko.mocnik@dem.si>
     Sorting for Slovenian language and the cset.tgz module for easier
     adding of other character sets.

"TAMITO" <tommy@valley.ne.jp>
     The _MB character sets macros and ujis and sjis character sets.

Yves Carlier <Yves.Carlier@rug.ac.be>
     mysqlaccess ; A program to show how the access right for a user.

Rhys Jones <rhys@wales.com> (And GWE Technologies Limited)
     For the JDBC; A module to extract data from *MySQL* with a Java
     client.

Dr Xiaokun Kelvin ZHU <X.Zhu@brad.ac.uk>
     Futher development of the JDBC driver and other *MySQL* related
     Java tools.

James Cooper <pixel@organic.com>
     For setting up a searchable mailing list archive at his site.

Rick_Mehalick <Rick_Mehalick@i-o.com>
     For xmysql a graphical X client for *MySQL*.

Doug Sisk <sisk@wix.com>
     For providing RPM packages of *MySQL* for RedHat Linux.

"Diemand Alexander V." <axeld@vial.ethz.ch>
     For providing RPM packages of *MySQL* for RedHat Linux/Alpha.

Antoni Pamies Olive <toni@readysoft.es>
     For providing RPM versions of a lot of *MySQL* clients for Intel
     and Sparc.

Jay Bloodworth <jay@pathways.sde.state.sc.us>
     For providing RPM versions for *MySQL* 3.21 versions.

Jochen Wiedmann <wiedmann@neckar-alb.de>
     Maintaining of the perl module DBD::mysql

Therrien Gilbert <gilbert@ican.net>, Jean-Marc Pouyot <jmp@scalaire.fr>
     French error messages.

Petr snajdr, <snajdr@pvt.net>
     Czech error messages.

Jaroslaw Lewandowski <jotel@itnet.com.pl>
     Polish error messages

Miguel Angel Fernandez Roiz
     Spanish error messages

Roy-Magne Mo <rmo@www.hivolda.no>
     Norwegian error messages and testing of 3.21.#

Timur I. Bakeyev <root@timur.tatarstan.ru>
     Russian error messages

brenno@dewinter.com
     Italian error messages

Dirk Munzinger <dirk@trinity.saar.de>
     German error messages

David Sacerdote <davids@secnet.com>
     Ideas for secure checking of DNS hostnames

Gianmassimo Vigazzola" <qwerg@mbox.vol.it> or <qwerg@tin.it>
     Port to Win32/NT.

Irena Pancirov <irena@mail.yacc.it>
     Win32 port with Borland compiler.

Wei-Jou Chen <jou@nematic.ieo.nctu.edu.tw>
     Some support for Chinese(BIG5) characters.

Zeev Suraski <bourbon@netvision.net.il>
     from_unixtime time formating, ENCRYPT() functions, and bison
     adviser.  Active mailing list member.

Luuk de Boer <luuk@wxs.nl>
     Ported (and extended) the benchmark suite to DBI/DBD.  Some new
     date functions.

Jay Flaherty <fty@utk.edu>
     Big parts of the perl DBI/DBD section in the manual.

Paul Southworth <pauls@etext.org>, Ray Loyzaga <yar@cs.su.oz.au>,  Paul DuBois <paul@snake.net>.
     Proof-reading of the reference manual.

Alexis Mikhailov <root@medinf.chuvashia.su>
     User definable functions (UDF); CREATE FUNCTION and DROP FUNCTION.

Ross Wakelin <R.Wakelin@march.co.uk>
     Help to set up InstallShield for MySQL-win32.

Jethro Wright III <jetman@li.net>
     libmysql.dll

James Pereria <jpereira@iafrica.com>
     Mysqlmanager; A Win32 gui tool for administrating *MySQL*.

Curt Sampson <cjs@portal.ca>
     Porting of MIT-pthreads to NetBSD/Alpha and NetBSD 1.3/i386.

Sinisa Milivojevic <sinisa@coresinc.com>
     Added compression (with zlib) to the client/server protocol.

   Other contributors, bugfinders and testers: James H. Thompson,
Maurizio Menghini, Wojciech Tryc, Luca Berra, Zarko Mocnik, Wim Bonis,
Elmar Haneke, jehamby@lightside, psmith@BayNetworks.COM,
duane@connect.com.au, "Ted Deppner <ted@psyber.com>, Mike Simons,
Jaakko Hyvtti.

   And lots of bug report/patches from the folks on the mailing list.

   And a big tribute to those that helps us answer question on the
mysql@tcx.se mailing list.

"Daniel Koch" <dkoch@amcity.com>
     IRIX setup.

"Luuk de Boer" <luuk@wxs.nl>
     Benchmark questions.

Tim Sailer <tps@users.buoy.com>
     DBD-mysql questions.

"Boyd Lynn Gerber (801) 250-O795 Work" <gerberb@zenez.com>
     SCO related questions.

"Mehalick RE (Richard)  at MSXSEPC" <RM186061@shellus.com>
     XmySQL releated questions and basic installation questions.

Zeev Suraski <bourbon@netvision.net.il>
     Apache module configuration questions (log & auth), PHP related
     questions, SQL syntax related questions and other general
     questions.

Francesc Guasch <frankie@citel.upc.es>
     General questions

Jonathan J Smith <jsmith@wtp.net>
     Questions pertaining to OS specifics with Linux, SQL syntax, and
     other things that might be needing some work.

David Sklar <sklar@student.net>
     Using *MySQL* from PHP and Perl.

Alistair MacDonald <A.MacDonald@uel.ac.uk>
     Not yet specified, but is flexible and can handle Linux and maybe
     HP-UX.  Will try to get user to use mysqlbug.

John Lyon <jlyon@imag.net>
     Questions about installing *MySQL* on Linux systems, using either
     .rpms, or compiling from source.

"Lorvid Ltd." lorvid@WOLFENET.com
     Simple billing/license/support/copyright issues.

Patrick Sherrill <patrick@coconet.com>
     ODBC and VisualC++ interface questions.

Randy Harmon <rjharmon@uptimecomputers.com>
     DBD, Linux, Some SQL syntax questions.

*MySQL* change history
**********************

Changes in release 3.22.x (Alpha version)
=========================================

   The 3.22 version has faster and safer connect code and a lot of new
nice enhancements.  The reason for not including these changes in the
3.21 version is mainly that we are trying to avoid big changes to 3.21
to keep it as stable as possible.  As there aren't really any MAJOR
changes, upgrading to 3.22 should be very easy and painless.

   3.22 also includes the new DBD-mysql (1.1830) driver that can use the
new connect protocol!

Changes in release 3.22.4
-------------------------

   * New option to mysqld: -tmpdir.

   * *MySQL* now automatically changes a query from an ODBC client:
     SELECT ... from table WHERE auto_increment_column IS NULL to
     SELECT ... from table WHERE auto_increment_column ==
     LAST_INSERT_ID().  This allows some ODBC programs (Delphi, Access)
     to retrieve the newly inserted row to fetch the auto_increment id.

   * Drop table now waits for all users to free a table before deleting
     it

   * Fixed small memory leak in the new connect protocol

   * New functions: BIN(), HEX() and CONV() for converting between
     different number bases.

   * Added function SUBSTRING() with 2 arguments.

   * If one created a table with smaller record length than 5, one
     couldn't delete rows from this table

   * Added optimization to remove const reference tables from ORDER BY
     and GROUP BY.

   * mysqld now automatically disables system locking on Linux, Win32
     and if one uses MIT-pthreads.  One can force the use of locking by
     doing: `--enable-locking'.

   * Added new mysqld option -console, to force a console window (for
     error messages) when using Win32.

   * Fixed table locks for Win32.

   * Allow '$' in identifiers.

   * Added optimization to remove const reference tables from ORDER BY
     and GROUP BY.

   * changed configure file name from `my.cnf' to `.my.cnf'

   * Added date_add() and date_sub() functions.

Changes in release 3.22.3
-------------------------

   * Fixed a lock problem (bug in *MySQL* 3.22.1) when closing
     temporary tables.

   * Added missing mysql_ping() to the client lib. Added 'ping' command
     to mysqladmin.

   * Added -compress option to all *MySQL* clients.

   * Changed 'byte' to 'char' in mysql.h and mysql_com.h.

Changes in release 3.22.2
-------------------------

   * Searching on multiple constant keys that matched > 30 % of the
     rows didn't always use the best possible key.

   * New functions:  <<, >>, rpad() and lpad().

   * One can now save default options (like passwords) in a config file
     (my.cnf).

   * Lots of small changes to get ORDER BY to work when no records are
     found when using fields that are not in GROUP BY (MySQL extension).

   * Added new option -chroot to mysqld to start mysqld in a chroot
     environment (by Nikki Chumakov <nikkic@cityline.ru>).

   * End space is now ignored when comparing case sensitive strings;
     This should fix some problems with ODBC and flag 512!

   * Fixed a core-dump bug in the range optimizer.

   * New flag to mysqld: -one-thread for debugging with LinuxThreads
     (or glibc).  (This replaces the -T32 flag)

   * Added DROP TABLE IF EXISTS to not get an error if the table
     doesn't exist.

   * IF and EXISTS are now reserved words (they would have to be sooner
     or later).

   * Added lots of new options to mysqldump.

   * Server error messages are now in mysqld_errror.h.

   * The server/client protocol now supports compression.

   * All bug fixes from *MySQL* 3.21.32.

Changes in release 3.22.1
-------------------------

   * Added new C-API function: mysql_ping().

   * Added new API functions: mysql_init() and mysql_options().  One
     MUST now call mysql_init() before one calls mysql_real_connect().
     One doesn't have to call mysql_init() if one only uses
     mysql_connect().

   * Added mysql_option(..,MYSQL_OPT_CONNECT_TIMEOUT) so one can set a
     timeout for connecting to a server.

   * Added -timeout argument to mysqladmin (as a test of
     mysql_options()).

   * Added options AFTER column and FIRST to ALTER TABLE ... ADD
     columns.  This makes is possible to add a new column at some
     specific location in an old table.

   * WEEK() now takes an optional argument to allow handling of weeks
     when week starts on Monday (Some European countries), or Sunday.
     The default WEEK() assumes week starts on Sunday().

   * TIME columns weren't stored properly (bug in *MySQL* 3.22.0).

   * UPDATE now returns update information about how many rows were
     matched and updated, and how many 'warnings' occurred when doing
     the update.

   * Fixed incorrect result from 'format(-100,2)'.

   * enum() and set() columns were compared binary; changed to be case
     insensitive.

Changes in release 3.22.0
-------------------------

   * New (backward compatible) connect protocol that allows one to
     specify the database to use when connecting to get much faster
     connections to a specific database.

            mysql_real_connect() call is changed to:
          
            mysql_real_connect(MYSQL *mysql,const char *host, const char *user,
          		     const char *passwd, const char *db,
          		     uint port, const char *unix_socket,uint client_flag)

   * Each connection is handled by its own thread, rather than by the
     master accept() thread.  This fixes permanently the telnet bug
     that was a topic on the mail list some time ago.

   * All TCP/IP connections are now checked with backward resolving of
     the hostname to get better security. mysqld has now a local
     hostname resolver cache so connections should actually be faster
     than before, even with this feature.

   * A site automatically will be blocked from future connections if one
     repeatedly connects with an 'improper header' (like when one uses
     telnet)

   * One can now reference to tables in different databases with:
     table@database or database.table.  This makes it possible to give
     a user read access to some tables and write access to others
     simply by keeping them in different databases!

   * If mysqld is started as root, it can now run as another user if
     the new -user option is specified.

   * Added caching of users & access rights (for faster access rights
     checking)

   * Normal users (not anonymous ones) can change their password with
     mysqladmin password 'new_password'.  This uses crypted passwords
     that are not logged in the normal mysql log!

   * All important string functions are now coded in assembler for x86
     Linux machines.  This gives a speedup of 10% in many cases.

   * For tables that have many columns the column names are now hashed
     for much faster column name lookup (this will speed up some
     benchmark tests a lot!)

   * Some benchmarks are changed to get better individual timing.
     (Some loops was so short that a specific test took < 2 seconds. The
     loops has been changed to take about 20 seconds to make it easier
     to compare different databases. 1 <-> 2  before is now 11 <-> 24
     which is much better)

   * Re-arranged select code to handle some very specific queries
     involving group functions (like COUNT(*)) without a GROUP BY but
     with HAVING. The following now works.

     SELECT count(*) as C from TABLE HAVING C > 1

   * Changed the protocol for field functions to be faster and avoid
     some mallocs().

   * Added flag -T32 to mysqld for running all queries under the main
     thread.  This makes it possible to debug mysqld under Linux with
     gdb!

   * Added optimization of 'not_null_column IS NULL' (needed for some
     Access queries)

   * Allow one to use STRAIGHT_JOIN between two tables to force the
     optimizer to join them in a specific order.

   * String functions now return VARCHAR() instead of CHAR() and the
     column type is now VARCHAR() for fields saved as VARCHAR().  This
     should make the MyODBC driver better, but may break some old
     *MySQL* clients that don't handle FIELD_TYPE_VARCHAR the same as
     FIELD_TYPE_CHAR.

   * CREATE INDEX and DROP INDEX are now implemented through ALTER
     TABLE.  CREATE TABLE is still the recommended (fast) way to create
     indexes.

   * Added option wait_timeout to mysqld.

   * Added time column to 'mysqladmin processes' to show how long a
     query has taken or how long a thread has slept.

   * Added lots of new variables to 'show variables' and some new to
     'show status'

   * Added new type: YEAR. YEAR is stored in 1 byte with range 0,
     1901-2155.

   * Added new DATE type that is stored in 3 bytes instead of 4. All new
     tables will created with the new date type if one doesn't use
     -old-protocol.

   * Fixed bug in record caches;  One could get 'Error from table
     handler: #' on some OS from some queries.

   * New configure option for x86 machines (tested on Linux + gcc):
     -enable-assembler.  This will enable assembler functions for the
     most important string functions for more speed!

Changes in release 3.21.x
=========================

Changes in release 3.21.33
--------------------------

   * Fixed problem when sending SIGHUP to mysqld; mysqld core dumped
     when starting from boot on some systems.

   * Fixed problem with loosing a little memory for some connections.

   * DELETE from table; without a condition is now done the long way
     when one uses LOCK TABLES or if the table is in use, to avoid race
     conditions.

   * INSERT INTO TABLE (timestamp_column) VALUES (NULL); didn't set
     timestamp.

Changes in release 3.21.32
--------------------------

   * Fixed some possible race conditions when using with *MySQL* and
     many reopen/close of the same tables under heavy load!  This could
     in some very rare case corrupt the header of the index file and
     cause error 126 or 138.

   * Fixed fatal bug in refresh() when running with -skip-locking here
     was a 'very small' time gap after a 'mysqladmin refresh' when a
     table can be corrupted if one thread updated a table while another
     thread did mysqladmin refresh and another thread started a new
     update at the same table before the first thread had finished.  A
     Refresh (or -flush-tables) will now not return until all used
     tables was closed!

   * SELECT DISTINCT with a WHERE clause that didn't match any rows
     returned a row in some context (bug only in 3.21.31)

   * GROUP BY + ORDER BY returned one empty row when no rows where
     found.

   * Fixed a bug in range optimizer that wrote: "Use_count: Wrong count
     for ..." in the error log file.

Changes in release 3.21.31
--------------------------

   * Fixed a sign extension problem for the type 'tiny' on IRIX.

   * Fixed problem with left("constant_string",function).

   * Fixed problem with find_in_set().

   * LEFT JOIN core dumped if the second table is used with a constant
     WHERE/ON expression with uniquely identifies one record.

   * Fixed problems with date_format() and wrong dates.  date_format()
     now ignores '%' to make it possible to extend it more easily in
     the future.

Changes in release 3.21.30
--------------------------

   * 'mysql' now returns a exit code > 0 if the query returned an error.

   * Save of command line history to file in mysql client.  by Tommy
     Larsen <tommy@mix.hive.no>

   * Fixed problem with empty lines that was ignored in mysql.cc

   * Save the pid of the signal handler thread in the pid file instead
     of the pid of the main thread.

   * Added patch by tommy@valley.ne.jp to support Japanese characters
     SJIS and UJIS.

   * Changed safe_mysqld to redirect startup messages to 'hostname'.err
     instead of 'hostname'.log to reclaim file space on 'mysqladmin
     refresh'

   * enum() had always the first entry as default value.

   * ALTER TABLE wrote two entires to the update log.

   * sql_acc() now closes the mysql privilege tables after a reload to
     save table space and memory.

   * Changed LOAD DATA to use less memory with tables and blobs.

   * Sorting on a function which made a division / 0 produced a wrong
     set in some cases.

   * Fixed select problem with LEFT() when using the czech character
     set.

   * Fixed problem in isamchk; It couldn't repair a packed table in a
     very unusual case.

   * Selects with & or | (bit functions) failed on columns with NULL
     values.

   * When comparing a field = field, where one of the fields was a part
     key, only the length of the part key was compared.

Changes in release 3.21.29
--------------------------

   * LOCK TABLES + 'DELETE from table' never removed locks properly.

   * Fixed problem when grouping on a OR function.

   * Fixed permission problem with umask() and creating new databases.

   * Fixed permission problem on result file with SELECT ... INTO
     OUTFILE...

   * Fixed problem in range optimizer (core dump) for a very complex
     query.

   * Fixed problem when using MIN(integer) or MAX(integer) in GROUP BY.

   * Fixed bug on Alpha when using integer keys. (Other keys worked on
     Alpha).

   * Fixed bug in WEEK("XXXX-xx-01").

Changes in release 3.21.28
--------------------------

   * Fixed socket permission (clients couldn't connect to unix socket
     on Linux).

   * Fixed bug in record caches;  One could get 'Error from table
     handler: #' on some OS from some queries.

Changes in release 3.21.27
--------------------------

   * Added user level locks:  GET_LOCK(string,timeout),
     RELEASE_LOCK(string)

   * Added opened_tables to 'show status'.

   * Changed connect timeout to 3 seconds to make it somewhat harder
     for crackers to kill mysqld trough telnet + TCP/IP.

   * Fixed bug in range optimizer when using: WHERE key_part_1 >=
     something and key_part_2 <= something_else

   * Changed configure for detection of FreeBSD 3.0 9803xx and above

   * WHERE with string-column-key = constant-string didn't always find
     all rows if the column had many values differing only with
     characters of the same sort value (like e and ).

   * Strings keys looked up with 'ref' was not compared case
     sensitively.

   * Added umask() to make log_files non-readable for normal users.

   * Ignore users with old password (8 byte) on startup if not using
     -old-protocol.

   * select which matched all key fields returned the values in the same
     case as the matched values instead of the found values. (Minor
     problem)

Changes in release 3.21.26
--------------------------

   * from_days(0) now returns "0000-00-00"

   * In DATE_FORMAT() PM and AM was swapped for hours 00 and 12.

   * Extended the default max key size to 256.

   * Fixed bug when using BLOB/TEXT in GROUP BY with many tables.

   * A enum field that is not declared NOT NULL has NULL as default
     value.  (Before the default value was the first enum option)

   * Fixed bug in the join optimizer code when using many part keys on
     the same key:  INDEX (Organisation,Surname(35),Initials(35)).

   * Added some tests to the table order optimizer to get some cases
     with 'SELECT ... FROM many_tables' much faster.

   * Added a retry loop around accept() to possible fix some problems
     on some Linux machines.

Changes in release 3.21.25
--------------------------

   * Changed typedef 'string' to 'my_string' for better portability.

   * One can now kill threads that are waiting for 'disk full'.

   * Fixed some problems with UDF functions.

   * Added long options for isamchk. Try isamchk -help.

   * Fixed a bug when using 8 bytes long (alpha); filesort() didn't
     work.  Affects DISTINCT, ORDER BY and GROUP BY on 64 bit
     processors.

Changes in release 3.21.24
--------------------------

   * Dynamic loadable functions. Based on source from Alexis Mikhailov.

   * One couldn't delete from a table if no one had done a select on
     the table.

   * Fixed problem with range optimizer which many OR's on key parts
     inside each other.

   * Recoded min() and max() to work properly with strings and HAVING.

   * Changed default umask for new files from 0664 to 0660.

   * Fixed problem with LEFT JOIN and constant expressions in the ON
     part.

   * Added Italian error messages from <brenno@3cord.philips.nl>

   * configure now works better on OSF1 (tested on 4.0D).

   * Added hooks to allow LIKE optimization with international
     character support.

   * Upgraded DBI to 0.93

Changes in release 3.21.23
--------------------------

   * Fixed that the following symbols are not reserved words: TIME DATE
     TIMESTAMP TEXT BIT ENUM NO ACTION CHECK YEAR MONTH DAY HOUR MINUTE
     SECOND STATUS VARIABLES.

   * Setting a TIMSTAMP to NULL in LOAD DATA INFILE... didn't set the
     current time for the TIMESTAMP.

   * Fix that BETWEEN recognizes binary strings. Now BETWEEN is case
     sensitive.

   * Added switch -skip-thread-priority for systems where mysqld's
     thread scheduling doesn't work properly (BSDI 3.1).

   * Added ODBC functions DAYNAME() and MONTHNAME().

   * Added function TIME_FORMAT().  This works like DATE_FORMAT() but
     takes a time string (HH:MM:DD) as argument.

   * Fixed unlikely(?) key optimizer bug when using ORs of key parts
     inside ANDs.

   * Added command 'variables' to mysqladmin.

   * A lot of small changes to the binary releases.

   * Fixed a bug in the new protocol from *MySQL* 3.21.20.

   * Changed ALTER TABLE to work with WIN32 (Win32 can't rename open
     files).  Fixed also a couple of small bugs in the WIN32 version.

   * All standard *MySQL* clients are now ported to MySQL-win32.

   * *MySQL* can now be started as a service on NT.

Changes in release 3.21.22
--------------------------

   * Starting with this version all *MySQL* distributions will be
     configured, compiled and tested with crash-me and the benchmarks
     on the following platforms: SunOS 5.6 sun4u, SunOS 5.5.1 sun4u,
     SunOS 4.14 sun4c, SunOS 5.6 i86pc, IRIX 6.3 mips5k, HP-UX 10.20
     hppa, AIX 4.2.1 ppc, OSF1 V4.0 alpha, FreeBSD 2.2.2 i86pc and BSDI
     3.1 i386.

   * Fix of count(*) problems when the WHERE clause didn't match any
     records.  (Bug from 3.21.17)

   * Removed that NULL = NULL is true.  Now one must use IS NULL or IS
     NOT NULL to test if a value is NULL. (This is according to ANSI
     SQL but may break old applications that are ported from mSQL) One
     can get the old behaviour by compiling with -DmSQL_COMPLIANT

   * Fixed bug that core dumped when using many LEFT OUTER JOIN's.

   * Fixed bug in ORDER BY on string formula with possible NULL values.

   * Fixed problem in range optimizer when <= on sub index.

   * Added functions DAYOFYEAR(), DAYOFMONTH(), MONTH(), YEAR(), WEEK(),
     QUARTER(), HOUR(), MINUTE(), SECOND() and FIND_IN_SET().

   * Added command SHOW VARIABLES.

   * Added support of 'long constant strings' from ANSI SQL: select
     'first ' 'second';  -> 'first second';

   * Upgraded mSQL-Mysql-modules to 1.1825

   * Upgraded mysqlaccess to 2.02

   * Fixed problem with Russian character set and LIKE.

   * Ported to openbsd 2.1

   * New Dutch error messages

Changes in release 3.21.21a
---------------------------

   * Configure changes for some OS.

Changes in release 3.21.21
--------------------------

   * Fixed optimizer bug when using 'WHERE data_field=date_field2 and
     date_field2=constant'

   * Added command 'show status'

   * Removed manual.ps from the source distribution to make it smaller.

Changes in release 3.21.20
--------------------------

   * Changed maximum table name and column name lengths from 32 to 64.

   * Aliases can now be of 'any' length.

   * Fixed that 'mysqladmin stat' returns right number of queries.

   * Changed protocol (downward compatible) to mark if a column is
     auto_increment or a timestamp. This is needed for the new Java
     driver.

   * Added hebrew sorting order by Zeev Suraski.

   * Solaris 2.6: Fixed configure bugs and increased maximum table size
     from 2G to 4G

Changes in release 3.21.19
--------------------------

   * Upgraded DBD to 1823. This version implements mysql_use_result in
     DBD-Mysql.

   * Benchmarks updated for empress (by Luuk)

   * Fixed a case of slow range searching.

   * Configure fixes (Docs directory).

   * Added function `REVERSE()' (by Zeev Suraski)

Changes in release 3.21.18
--------------------------

   * Give error message if client C functions are called in wrong order.

   * Added automatic reconnect to the libmysql.c library. If a write
     command fails a automatic reconnect is done.

   * Small sort sets doesn't use temporary files anymore.

   * Upgraded DBI to 0.91

   * Fixed a couple of problems with LEFT OUTER JOIN.

   * Added CROSS JOIN syntax. CROSS is now a reserved word.

   * Recoded yacc/bison stack allocation to be even safer and allow
     *MySQL* to handle even bigger expressions.

   * Fixed a couple of problems with the update log.

   * ORDER BY was slow when used with key ranges.

Changes in release 3.21.17
--------------------------

   * Changed documentation string of -with-unix-socket-path to avoid
     confusion.

   * Added ODBC and ANSI SQL style `LEFT OUTER JOIN'.

   * The following are new reserved words: `LEFT', `NATURAL', `USING'

   * The client library is now using the environment variable
     `MYSQL_HOST' as the default host if it's defined.

   * `SELECT column, SUM(expr)' now returns `NULL' for column when
     there are matching rows.

   * Fixed problem with compare of binary strings and blobs with ASCII
     characters over 127.

   * Fixed lock problem: When freeing a read lock on a table with
     multiple read locks, a thread waiting for write lock would have
     given the lock.  This shouldn't affect data integrity, but could
     possible make mysqld to restart if one thread was reading data
     that another thread modified.

   * LIMIT offset,count didn't work in INSERT ... SELECT.

   * Optimized key block caching. This will be quicker than the old one
     when using bigger key caches.

Changes in release 3.21.16
--------------------------

   * Added ODBC 2.0 & 3.0 functions: `POWER()', `SPACE()', `COT()',
     `DEGREES()', `RADIANS()', `ROUND(2 arg)' and `TRUNCATE()'.

   * *WARNING INCOMPATIBLE CHANGE!!*. `LOCATE()' parameters where
     swapped according to ODBC standard. Fixed.

   * Added function `TIME_TO_SEC()'.

   * In some cases default values was not used for `NOT NULL' fields.

   * Timestamp wasn't updated in `UPDATE SET ...' if the timestamp was
     used as.

   * Allow empty strings as default values for `BLOB' and `TEXT' to be
     compatible with mysqldump.

Changes in release 3.21.15
--------------------------

   * *WARNING INCOMPATIBLE CHANGE!!* mysqlperl is now from
     Msql-Mysql-modules. This means that the connect() now takes
     host,database,user,password! The old version took
     host,database,password,user.

   * Allow `DATE '1997-01-01'', `TIME '12:10:10'' and `TIMESTAMP
     '1997-01-01 12:10:10'' formats required by ANSI SQL.  *WARNING
     INCOMPATIBLE CHANGE!!* This has the unfortunate side-effect that
     one can't have columns named `DATE', `TIME' or `TIMESTAMP' anymore
     :( Old columns can still be accessed trough 'tablename.columnname'!

   * Changed Makefiles to hopefully work better with BSD systems. Also
     manual.dvi is now included in the distribution to avoid having
     stupid makes trying to rebuild it.

   * Readline library upgraded to version 2.1

   * A new sortorder german-1. That is a normal iso-latin1 with a
     german sort order.

   * Perl DBI/DBD is now included in the distribution. DBI is now the
     recommended way to connect to *MySQL* from perl.

   * New portable benchmark suite with DBD, with test results from mSQL
     2.0.3, *MySQL*, PostgreSQL 6.2.1 and Solid server 2.2.

   * crash-me is now included with the benchmarks; This is a perl
     program designed to find as many limits as possible in a SQL
     server. Tested with mSQL, postgreSQL, Solid and *MySQL*.

   * Fixed bug in range-optimiser that crashed mysql on some queries.

   * Table and column name completion for mysql command line tool, by
     Zeev Suraski and Andi Gutmans.

   * Added new command `REPLACE', which works like `INSERT' but
     replaces conflicting records with the new record. `REPLACE INTO
     TABLE ... SELECT ...' works also.

   * Added new commands: `CREATE DATABASE db_name' and `DROP DATABASE
     db_name'.

   * Added `RENAME' option to `ALTER TABLE': `ALTER TABLE name RENAME
     AS new_name'.

   * make_binary_distribution now includes libgcc.a in
     libmysqlclient.a. This should make linking work for people without
     gcc.

   * Changed `net_write()' to `my_net_write()' because of name conflict
     with sybase.

   * New function `DAYOFWEEK()' compatible with ODBC.

   * Stack checking and bison memory overrun checking to get *MySQL*
     safer with weird queries.

Changes in release 3.21.14b
---------------------------

   * Fixed a couple of small configure problems on some platforms.

Changes in release 3.21.14a
---------------------------

   * Ported to SCO Openserver 5.0.4  with FSU-threads.

   * HP-UX 10.20 should work.

   * Added new function DATE_FORMAT()

   * Added NOT IN.

   * Added automatic removal of 'ODBC function conversions': {fn now() }

   * Handle ODBC 2.50.3 option flags.

   * Fixed compare of DATE and TIME with NULL.

   * Changed language name from germany to german to be consistent with
     the other language names.

   * Fixed sorting problem on functions returning a float. Before the
     values was converted to a int before sorting.

   * Fixed slow sorting when sorting on key field when using
     KEY_COLUMN=constant.

   * SORTING on calculated DOUBLE values sorted on integer results
     instead.

   * 'mysql' doesn't need a database argument anymore.

   * Changed the place where HAVING should be. According to ANSI it
     should be after GROUP BY but before ORDER BY. *MySQL* 3.20 had it
     wrongly last.

   * Added Sybase command: USE DATABASE to start using another database.

   * Added automatic adjusting of number of connections and table cache
     size if the maximum number of files that can be opened are less
     than needed.  This should fix that mysqld doesn't crash even if
     one hasn't done a ulimit -n 256 before starting mysqld.

   * Added lots of limit checks to make it safer when running with too
     little memory or when doing weird queries.

Changes in release 3.21.13
--------------------------

   * Added retry of interrupted reads and clearing of errno.  This
     makes Linux systems much safer!

   * Fixed locking bug when using many alias on the same table in the
     same select.

   * Fixed bug with LIKE on number key.

   * New error message so one can check if the connection was lost while
     the command was running or if the connection was down from the
     start.

   * Added -table option to mysql to print in table format.  Moved time
     and row information after query result.  Added automatic reconnect
     of lost connections.

   * Added != as an alias for <>.

   * Added function VERSION() to make easier logs.

   * New multi-user test 'tests/fork_test.pl' to put some strain on the
     thread library.

Changes in release 3.21.12
--------------------------

   * Fixed ftruncate() call in MIT-pthreads. This made isamchk()
     destroy the .ISM files on (Free)BSD systems 2.#

   * Fixed broken __P_ patch in MIT-pthreads

   * Many memory overrun checks. All string functions now return `NULL'
     if the returned string should be longer than `max_allowed_packet'.

   * Changed the name if the `INTERVAL' type to `ENUM', because
     `INTERVAL' is used in ANSI SQL.

   * In some cases doing a JOIN + GROUP + INTO OUTFILE, the result
     wasn't grouped.

   * LIKE with '_' as last character didn't work. Fixed

   * Added extended ANSI SQL `TRIM()' function.

   * Added `CURTIME()'.

   * Added `ENCRYPT()' function by Zeev Suraski.

   * Fixed better `FOREIGN KEY' syntax skipping. New reserved words:
     `MATCH', `FULL', `PARTIAL'

   * mysqld now allows ip and hostname to the `--bind-address' option.

   * Added "SET OPTION CHARACTER SET cp1251_koi8" to enable conversions
     off data to/from cp1251_koi8.

   * Lots of changes for Win95 port. In theory this version should now
     be easily portable to Win95.

   * Changed the create column syntax off `NOT NULL' to be after the
     `DEFAULT' value as specified in the ANSI SQL standard. This will
     make mysqldump with `NOT NULL' and default values incompatible with
     *MySQL* 3.20.

   * Added a lot of function name alias so one can use the functions
     with ODBC or ANSI SQL92 syntax.

   * Fixed `ALTER TABLE person ALTER COLUMN phone SET DEFAULT NULL'
     syntax.

   * Added CHAR and BIT as a synonyms for CHAR(1)

   * Fixed core dump when updating as user with only select privilege.

   * INSERT ... SELECT ... GROUP BY didn't work in some cases. On got
     'Invalid use of group function'

   * When using LIMIT, SELECT now always uses keys instead of record
     scan.  This will give better performance on SELECT and a WHERE
     that matches many rows.

   * Added Russian error messages.

   * In some cases doing a join + group + INTO OUTFILE, the result
     wasn't grouped.

Changes in release 3.21.11
--------------------------

   * Configure changes.

   * *MySQL* now works with the new thread library on BSD/OS 3.0.

   * Added new group functions: BIT_OR() and BIT_AND().

   * Added compatibility functions: CHECK, REFERENCES. CHECK is now a
     reserved word.

   * Added BIT as a synonym for CHAR(1) to get better compatibility.

   * Added option ALL to GRANT for better compatibility. (GRANT is still
     a dummy fuction.

   * Added partly translated dutch messages.

   * Fixed bug in ORDER BY and GROUP BY with NULL columns

   * Added function last_insert_id() to retreive last auto_increment
     value.  This is for clients to ODBC that can't use the
     mysql_insert_id API function, but can be used by any client.

   * Added option '-flush-logs' to mysqladmin.

   * Added command 'status' to mysql.

   * Fixed problem with order/group by because of bug in gcc.

   * Fixed problem with INSERT ... SELECT .. GROUP BY.

Changes in release 3.21.10
--------------------------

   * New mysqlaccess.

   * CREATE supports now all ODBC types and the mSQL `TEXT' type. All
     ODBC 2.5 functions is also supported (added REPAT). This gives
     better portability.

   * Added text types: `TINYTEXT', `TEXT', `MIDDLETEXT' and `LONGTEXT'.
     These are actually blobs, but all searching is done case
     independent.

   * All old `BLOB' fields are now `TEXT' fields.  This only changes
     that all searching on strings are case independent. One have to do
     a ALTER TABLE and change the field to BLOB if one wants to have
     tests done case dependent.

   * Fixed some configure issues.

   * Made the locking code a bit safer. Fixed very unlikely dead lock
     situation.

   * Fixed a couple of bugs in the range optimiser. Now the new range
     benchmark test-select works.

Changes in release 3.21.9
-------------------------

   * Added -enable-unix-socket=pathname arg to configure.

   * Fixed a couple of portable problems with include files.

   * Fixed bug in range calculation that could return empty set when
     searching on multiple key with only one entry (very rare).

   * Most things ported to FSU threads, which should allow *MySQL* to
     run on SCO. *Note SCO::.

Changes in release 3.21.8
-------------------------

   * Works now in Solaris 2.6

   * Added handling of calculation of sum() functions.  One can now use
     for example: SUM(column)/COUNT(column)

   * Added handling of trigometric functions: PI(), ACOS(), ASIN(),
     ATAN(), COS(), SIN() and TAN().

   * New languages: norwegian, norwegian-ny and portuguese.

   * Fixed parameter bug in net_print in procedure.cc.

   * Fixed a cople of memory leaks.

   * Now allow also the old SELECT ... INTO OUTFILE syntax.

   * Fixed bug with group by and select on key with many values.

   * mysql_fetch_lengths() returned sometimes wrong lengths when one
     used mysql_use_result(). This affected at least some cases of
     mysqldump -quick.

   * Fixed bug in optimisation of WHERE const op field.

   * Fixed problem when sorting on NULL fields.

   * Fixed a couple of 64bit (Alpha) problems

   * Added option -pid-file=# to mysqld

   * Added date formating to from_unixtime(), originally by Zeev
     Suraski.

   * Fixed bug in BETWEEN in range optimiser (Did only test = of the
     first argument).

   * Added machine dependent files for MIT-pthreads i386-SCO. There is
     probably more to do to get this to work on SCO 3.5.

Changes in release 3.21.7
-------------------------

   * Changed to Makefile.am to take advantage of automake 1.2.

   * Added the beginnings of a benchmark suite.

   * Added more secure password handling.

   * Added new client function: mysql_errno() to get the error number of
     the error message. This makes error checking in the client much
     easier.  This makes the new server incompatible with the 3.20.#
     server when running without -old-protocol.  The client code is
     backward compatible.  More information can be found in the README
     file!

   * Fixed some problems when using very long, illegal names.

Changes in release 3.21.6
-------------------------

   * Fixed more portability issues (wrong sigwait and sigset define)

   * configure should now be able to detect the last argument to
     accept().

Changes in release 3.21.5
-------------------------

   * Should now work at FreeBSD 3.0, if one used the
     FreeBSD-3.0-libc_r-1.0.diff which can be found at
     `http://www.tcx.se/Download/Patches'

   * Added new option to mysqld: -O tmp_table_size=#

   * New function from_unixtime(timestamp) which returns a date string
     in YYYY-MM-DD HH:MM:DD format.

   * New function sec_to_time(seconds) which returns a string in
     H:MM:SS format.

   * new function: substring_index(), originally by Zeev Suraski.

Changes in release 3.21.4
-------------------------

   * Should now configure and compile on OSF1 4.0 with the Dec compiler.

   * configure and compile on BSD/OS 3.0 works, but due to some bugs in
     BSD/OS 3.0, mysqld doesn't work on it yet.

   * configure and compile on FreeBSD 3.0, but I couldn't get
     pthread_create to work.

Changes in release 3.21.3
-------------------------

   * Added reverse check lookup of hostnames to get better security.

   * Fixed some possible buffer overflows if one uses too long
     filenames.

   * mysqld doesn't accept hostnames that starts with digits followed
     by a '.'  because the hostname may look like a IP.

   * Added option -skip-networking to only allow socket connections.
     (This will not work with MIT-pthreads!)

   * Added check of too long table names for alias.

   * Added check if database name is okey.

   * Addded check if too long table names.

   * Removed wrong free() that killed the server on 'create/drop
     database'.

   * Changed the name of some mysqld -O options to better names.

   * Added option '-O join_cache_size=#'.

   * Added option '-O max_join_size=#' to be able to set a limit how big
     queries (in this case big = slow) one should be able to handle
     without specifying 'SQL_OPTION OPTION_BIG_SELECTS=1'.  A # = is
     about 10 examined records. The default is 'unlimited'.

   * When comparing a TIME, DATE, DATETIME or TIMESTAMP column to a
     constant the constant is converted to a time value before
     comparing.  This will make it easier to get ODBC and particularly
     Access97 to work with the above types. It should also make dates
     easier to use and the compares should be quicker than before.

   * Applied patch from Jochen Wiedmann that fixes that query() in
     mysqlperl now can take queries with \0 in it.

   * Store of timestamp with 2 digit year YYMMDD didn't work.

   * Fix that timestamp isn't automatically updated if set in a update
     clause.

   * Now the automatic timestamp field is the FIRST timestamp field.

   * SELECT * INTO OUTFILE, which didn't correctly if the outfile
     already existed.

   * 'mysql' now shows thread id when starting or doing a reconnect.

   * Changed the default sort buffer size from 2M to 1M.

Changes in release 3.21.2
-------------------------

   * The range optimiser is cooded, but only 85% tested. It can be
     enabled with -new, but it crashes core a lot yet...

   * More portable. Should compile one AIX and alpha-digital.  At least
     the isam library should be relative 64 bit clean.

   * New isamchk which can detect and fix more problems.

   * New options for isamlog.

   * Using new version of automake

   * Many small portability changes (from the AIX and alpha-digital
     port) Better checking of pthread(s) library.

   * czech error messages by snajdr@pvt.net

   * 'mysql' now shows thread id when starting or doing a reconnect.

   * Decresed some buffers to get less problems on system with little
     memory.  Also added more checks to handle 'out of memory' problems

   * mysqladmin: One can now do 'mysqladmin kill 5,6,7,8'

   * When the max connection limit is reached, one extra connection by
     a user with the PROCESS_ACL privilege is granted.

   * Added new mysqld option: -O backlog=#

   * Increased max packet size from 512K to 1024K for client.

   * Almost all of the functions code is now tested in the intern test
     suite.

   * ALTER TABLE now returns warnings from field conversions.

   * Port changed to 3306 (got it reserved from ISI).

   * Added a fix for Visual Fox Base so that any schema name from a
     table specification is automatically removed.

   * New function ASCII.

   * Removed the between() function. On should use the 'col BETWEEN a
     AND b' syntax instead.

   * *MySQL* now doesn't anymore have to use a extra temporary table
     when sorting on functions or SUM functions.

   * Fixed bug that one couldn't use 'table_name.field_name' in UPDATE.

   * Fixed SELECT DISTINCT when using 'hidden group'. For example:
     SELECT DISTINCT MOD(some_field,10) FROM test GROUP BY some_field;
     Note: some_field is normally in the select part. ANSI SQL should
     require it.

Changes in release 3.21.0
-------------------------

   * New keywords used: INTERVAL, EXPLAIN, READ, WRITE, BINARY

   * Added ODBC functions CHAR(num,...) and ASCII(string).

   * Removed function BETWEEN(a,b,c). One should use the standard ANSI
     SYNTAX: expr BETWEEN expr AND expr.

   * New operator IN. This uses a binary search to find a match.

   * New command `LOCK TABLES table_name [AS alias] (READ | WRITE), ...'

   * New server option `mysqld --log-update' to get a log suitable for
     incremental updates

   * new command: EXPLAIN SELECT ... to get info about how the optimzier
     will do the join.

   * For easier client code, the client shouldn't anymore use
     `FIELD_TYPE_TINY_BLOB', `FIELD_TYPE_MEDIUM_BLOB',
     `FIELD_TYPE_LONG_BLOB' or `FIELD_TYPE_VAR_STRING' (as previously
     returned by mysql_list_fields).  One should instead only use
     `FIELD_TYPE_BLOB' or `FIELD_TYPE_STRING'.  If one wants exact
     types one should use the command `SHOW FIELDS' .

   * Added varbinary syntax: `0x######' which can be used as a string
     (default) or a number.

   * `FIELD_TYPE_CHAR' is renamed to `FIELD_TYPE_TINY'.

   * Changed all fields to C++ classes.

   * Removed FORM struct.

   * A field with a `DEFAULT' doesn't have to be `NOT NULL' anymore.

   * New field types:
    `ENUM'
          A string with only can take a couple of defined values. The
          value is stored as a 1-3 byte number that automatically is
          mapped to a string.  This is sorted according to string
          positions!

    `SET'
          A string with may have one or many string values separated
          with ','.  The string is stored as a 1,2,3,4 or 8 byte number
          where each bit stands for a specific string.  This is sorted
          according to unsigned value of the stored packed number.

   * Now all function calculation is done with double or long long.
     This will give one the full 64 bits range with bit functions and
     fix some conversions that previously could give precision losses.
     One should avoid using 'unsigned long long' columns with full 64
     bits range (numbers bigger than 9223372036854775807) because
     calculations is done with signed long long.

   * ORDER BY will now put NULL fields first. GROUP BY will also work
     with NULL.

   * Full WHERE with expressions.

   * New range optimiser with can resolve ranges when some prefix
     keypart is constant. Example: SELECT * FROM table_name WHERE
     key_part_1="customer" and key_part_2 >= 10 AND key_part_2 <= 10)

Changes in release 3.20.x
=========================

   Changes from 3.20.18 to 3.20.32b are not documented here since the
the 3.21 release bransched here. And the relevant changes are also
documented as changes to the 3.21 version.

Changes in release 3.20.18
--------------------------

   * Added -p# (remove # directories from path) to isamlog.  All files
     are written with a relative path from the database directory Now
     mysqld shouldn't crash on shutdown when using -log-isam.

   * New mysqlperl version. Is now compatible with msqlperl-0.63.

   * New DBD module available in Contrib/

   * Added group function STD() (standard derivation).

   * The mysql server is now by default compiled without debugging
     information.  This will make the daemon smaller and faster.

   * Now one usually only have to give -basedir to mysqld. All other
     paths are relative in a normal installation.

   * BLOBs contained sometimes garbage when used with a SELECT on more
     than one table and ORDER BY.

   * Fixed that calculations that are not in GROUP BY works as expected.
     (ANSI SQL extension) Example: SELECT id,id+1 FROM table GROUP BY id

   * The test of using MYSQL_PWD was reversed. Now MYSQL_PWD is enabled
     as default in the default release.

   * Fixed convert bug which got mysqld to core dump with Aritmetic
     error on Sparc-386

   * Added option -unbuffered to mysql. (For new mysqlaccess)

   * When using overlapping (unnecessary keys) and join over many tables
     the optimiser could get confused and return 0 records.

Changes in release 3.20.17
--------------------------

   * One can now use BLOBs columns and the functions IS NULL and IS NOT
     NULL in the WHERE clause.

   * All communication packages and row buffers are now alloced
     dynamically on demand. The default `max_allowed_packet' is now 65K
     for the server and 512K for the client. This is mainly used to
     catch wrong packets that could trash all memory. The server limit
     may be changed when it is started.

   * Changed stack usage to use less memory.

   * Changed safe_mysqld to check for running daemon.

   * The `ELT()' function is renamed to `FIELD()'.  The new `ELT()'
     function returns a value based on an index: `FIELD()' is the
     invers of `ELT()' Example: `ELT(2,"A","B","C")' returns `"B"'.
     `FIELD("B","A","B","C")' returns `2';

   * COUNT(field) where field could have a NULL value now works.

   * A couple of bug fixed in SELECT .. GROUP BY.

   * Fixed memory overrun bug in WHERE with many unoptimisable brace
     levels.

   * Fixed some small bugs in the grant code.

   * If hostname isn't found by get_hostname, only the IP is checked.
     Before one one got 'Access denied'

   * Inserts of timestamps with values didn't always work.

   * INSERT INTO ... SELECT .. WHERE could give the error 'Dupplicated
     field'

   * Added some tests to safe_mysqld to make it 'safer'

   * LIKE was case sensitive in some places and case insensitive in
     other.  Now `LIKE' is always case insensitive.

   * mysql.cc; Allow '#' anywhere on the line.

   * New command 'SET OPTION SQL_SELECT_LIMIT=#'. Se the FAQ for more
     details.

   * New version of the mysqlaccess script

   * Change from_days() and weekday() to also take a full timestamp or
     a datetime as argument. Before they only took a number of type
     YYYYMMDD or YYMMDD.

   * Added new function unix_timestamp(timestamp_column);

Changes in release 3.20.16
--------------------------

   * More changes in MIT-pthreads to get them safer. Fixed also some
     link bugs at least in SUNOS.

   * Changed mysqld to go around a bug in MIT-pthreads. This makes
     multiple small selects 20 times faster. Now lock_test.pl should
     work.

   * Added mysql_FetchHash(handle) to mysqlperl

   * The mysqlbug script is now distributed built to allow for reporting
     bugs that appear during the build with it.

   * Changed libmysql.c to prefer to use getpwuid() insted of cuserid().

   * Fixed bug in select optimiser when using many tables with the same
     column used as key to different tables.

   * mysql.cc; Allow '#' anywhere on the line.

   * Added new latin2 and Russian KOI8 character tables.

   * Added support for a dummy GRANT command satisfy Powerbuilder.

Changes in release 3.20.15
--------------------------

   * Fixed fatal bug 'packets out of order' when using MIT-pthreads.

   * Removed possible loop when thread waits for command from client
     and fcntl() fails. Thanks to Mike Bretz for finding this bug

   * Changed alarm loop in mysqld.cc because shutdown didn't always
     succeed in Linux.

   * Removed use of termbits from mysql.cc  This conflicted with glibc
     2.0

   * Fixed some syntax errors for at least BSD and Linux.

   * Fixed bug when doing a select as superuser without a database.

   * Fixed bug when doing SELECT with group calculation to outfile.

Changes in release 3.20.14
--------------------------

   * If one gives '-p' or -password to mysql without an argument, the
     password will be asked from the tty.

   * Added default password from MYSQL_PWD. (by Elmar Haneke)

   * Added commando 'kill' to mysqladmin to kill a specific mysql
     thread.

   * Sometimes when doing a reconnect on a down connection this
     succeeded first on second try.

   * Fixed adding a auto_increment key with ALTER_TABLE.

   * AVG() gave too small value on some selects with GROUP BY and ORDER
     BY.

   * Added new DATETIME type (by Giovanni Maruzzelli
     <maruzz@matrice.it>)

   * Fixed that define 'DONT_USE_DEFAULT_FIELDS' works

   * Changed to use a thread to handle alarms instead of signals on
     Solaris to avoid race conditions.

   * Fixed default length of signed numbers. (George Harvey
     <georgeh@pinacl.co.uk>)

   * Allow anything for CREATE INDEX.

   * Add prezeros when packing numbers to DATE, TIME and TIMESTAMP.

   * Fixed a bug in OR of multiple tables (Gave empty set).

   * Added many patches to MIT-pthreads. This fixes at least one lookup
     bug.

Changes in release 3.20.13
--------------------------

   * Added ANSI SQL94 DATE and TIME types.

   * Fixed bug in select with and-or levels.

   * Added support for Slovenian characters. The Contrib directory
     contains source and instructions to add other character sets.

   * Fixed bug with limit and order by.

   * Allow order and group on items that isn't in the select list.
     (Thanks to Wim Bonis <bonis@kiss.de> for pointing this out)

   * Allow setting of timestamp values in INSERT.

   * Fixed bug with SELECT ... WHERE ... = NULL.

   * Added changes for glibc 2.0. To get glibc to work one should add
     the gibc-2.0-sigwait-patch before compiling glibc.

   * Fixed bug in alter table when changeing a not null field to allow
     NULLs.

   * Added some ANS92 synonyms as field types to CREATE TABLE.  CREATE
     TABLE now allows FLOAT(4) and FLOAT(8) to mean FLOAT and DOUBLE.

   * new utility program mysqlaccess by Yves.Carlier@rug.ac.be.  This
     program shows the access rights for a specific user and the grant
     rows which determinate this grant.

   * Added WHERE const op field (by bonis@kiss.de)

Changes in release 3.20.11
--------------------------

   * When using SELECT ... INTO OUTFILE all temporary tables are ISAM
     instead of HEAP to allow big dumps.

   * Changed date functions to be 'string functions'. This fixed some
     'funny' side effects when sorting on dates.

   * Extended ALTER TABLE according to SQL92.

   * Some minor compability changes.

   * Added -port and -socket to all utility programs and mysqld.

   * Fixed MIT-pthreads readdir_r(). Now mysqladmin create database and
     drop database should work.

   * Changed MIT-pthreads to use our tempnam. This should fix the 'sort
     aborted' bug.

   * Added sync of records count in sql_update. This fixed slow updates
     on first connection. (Thanks to Vaclav Bittner for the test)

Changes in release 3.20.10
--------------------------

   * New insert type: INSERT INTO ... SELECT ...

   * mediumblob fixed.

   * Fixed bug in ALTER TABLE and BLOBs.

   * SELECT ... INTO OUTFILE now creates the file in the current
     database directory.

   * DROP TABLE can now take a list of tables.

   * Oracle synonym DESCRIBE (DESC)

   * Changes to make_binary_distribution

   * Added some comments about conifgures c++ link test to installation
     instructions.

   * Added -without-perl to configure.

   * Lot's of small portability changes.

Changes in release 3.20.9
-------------------------

   * Alter table didn't copy null bit. This resulted that NULL fields
     where always NULL.

   * CREATE didn't take numbers as DEFAULT.

   * Some compatibility changes for SunOS.

   * Removed config.cache from old distribution.

Changes in release 3.20.8
-------------------------

   * Fixed bug with ALTER TABLE and multi part keys.

Changes in release 3.20.7
-------------------------

   * New commands: ALTER TABLE, SELECT ... INTO OUTFILE and LOAD DATA
     INFILE.

   * New functions: NOW()

   * Added new field: file_priv to mysql/user table.

   * New scripts 'add_file_priv' which add the new field 'file_priv' to
     the user table. This scripts must be executed if one wants to use
     the new SELECT ... INTO and LOAD DATA INFILE...  commands with a
     version of mysql less than 3.20.7.

   * Fixed bug in locking code, with made lock_test.pl test fail.

   * new files NEW and BUGS

   * Changed select_test.c and insert_test.c to include config.h

   * Added command 'status' to mysqladmin for short logging.

   * Increased max keys to 16 and max key parts to 15.

   * Use of sub keys. A key may now be a prefix of a string field.

   * Added option -k for mysqlshow to get key info for table.

   * Added long options to mysqldump.

Changes in release 3.20.6
-------------------------

   * Portable to more systems because of MIT-pthreads. This will
     automatically be used is configure can not find a -lpthreads
     library.

   * GNU style long options to almost all programs. Test with 'program
     -help'.

   * Some shared library support for linux.

   * The FAQ is now in .texi format and is available in .html, .text,
     .ps,

   * Added new sql function RAND([init])

   * Changed sql_lex to handle \0 unquoted, but the client can't send
     the query through the C api, because it takes a str pointer.  one
     have to use mysql_real_query() to send the query.

   * Added API function: mysql_get_client_info

   * mysqld now uses the N_MAX_KEY_LENGTH from nisam.h as the max
     allowed key length.

   * The following now works: "select filter_nr,filter_nr from filter
     order by filter_nr" Before you got the error: "Column: 'filter_nr'
     in order clause is ambiguous"

   * mysql now outputs \0 \t \n and \\ when writing tab separated
     output.  when encountering ascii 0, tab, newline or \. This is to
     allow printing of binary data in a portable format.  To get old
     behavior use -r (or -raw).

   * Added german error messages (60 of 80 error messages translated)

   * Added new api function: mysql_fetch_lengths(MYSQL_RES *) which
     returns a array of of column lengths (of type uint).

   * Fixed bug with IS NULL in where clause.

   * Changed the optimiser a little to get better results when
     searching on a key part.

   * Added select option STRAIGHT_JOIN to tell the optimiser that it
     should join tables in the given order.

   * Added support of comment starting with '-' in mysql.cc (Postgres
     syntax)

   * You can have select_expressions and table columns in a select which
     are not used in the group part. This makes it efficient to
     implement lookups.  The used column should be a constant for each
     group because the value is calculated only calculated once for the
     first found row in a group.
          SELECT id,lookup.text,sum(*) FROM test,lookup
          WHERE test.id=lookup.id group by id;

   * Fixed bug in SUM(function) (Could make core dump)

   * Changed auto_increment according to SQL_SYNTAX: INSERT into table
     (auto_field) values (0) inserted 0, but the SQL_SYNTAX stated it
     should insert a auto_increment value.

   * mysqlshow.c: Added number of records in table. Had to change the
     client code a little to fix this.

   * mysql now allows double " or "" in strings for embedded ' or ".

   * New math functions:  EXP, LOG, SQRT, ROUND, CEILING

Changes in release 3.20.3
-------------------------

   * The configure source now compiles a thread free client library
     `-lmysqlclient'. This is the only library that needs to be linked
     with client applications.  When using the binary releases one have
     to link with `-lmysql -lmysys -ldbug -lstrings' as before.

   * New readline from bash-2.0.

   * LOTS of small changes to configure and makefiles (and related
     source).

   * There should now be possible to compile in another directory using
     vpath. Tested with GNU Make 3.75.

   * safe_mysqld and mysql.server changed to be more compatible between
     the source and the binary releases.

   * LIMIT takes now one or two numerical arguments.  If one argument
     the argument indicates the maximum number of rows in a result. If
     two arguments the first arguments says the offset to the first row
     to return, the second is the maximum number of rows.  With this
     it's easy to do a poor mans next page/previous page www
     application.

   * Changed name of SQL function FIELDS to ELT.  Changed sql function
     INTERVALL() to INTERVAL().

   * Made SHOW COLUMNS a synonym for SHOW FIELDS.  Added compatibility
     syntax FRIEND KEY to create table. This creates in mysql a non
     unique key on the given columns.

   * Added CREATE INDEX and DROP INDEX as compatibility functions. In
     mysql CREATE INDEX only checks if the index exists and gives an
     error if it doesn't exists. DROP INDEX always succeeds.

   * mysqladmin.c: Added client version to version info.

   * Fixed core dump bug in sql_acl (core on new connection).

   * Removed host,user and db tables from database test in the
     distribution.

   * FIELD_TYPE_CHAR can now be signed (-128 - 127) or unsigned (0 -
     255) Before it was always unsigned.

   * Bug fixes in concat(), weekday()

   * Changed a lot of source to get mysqld to be compiled with SUNPRO
     compiler.

   * SQL functions must now have a '(' directly after the function name.
     user '(' is now regarded as an identifier and a '('

Changes in release 3.20.0
-------------------------

   * The source distribution is done with configure and automake: It
     will make porting much easier.  Readline is included in the
     distribution.

   * Separate client compilation: The client code should be very easy
     to compile on system which doesn't have threads.

   * The old perl interface code is automatically compiled and
     installed.  Automatic compiling of DBD will follow when the new
     DBD code is ported.

   * Dynamic language support: mysqld can now be started with Swedish
     or English (default) error messages.

   * new functions: INSERT(),RTRIM(),LTRIM() and FORMAT().

   * mysqldump now works correctly for all field types (even
     auto_increment). The format for 'show fields from table' is changed
     so the 'type' column contains info suitable for 'CREATE TABLE'.
     In previous releases some CREATE TABLE info had to be patched to
     when recreating tables

   * Some parser bugs from 3.19.5 (blob and timestamp) are corrected.
     Timestamp now returns different date info depending of it's create
     length.

   * Changed parser to allow a database name, table name and field name
     to start with a number or '_'.

   * All old C code from UNIREG changed to c++ and cleaned up. This
     makes the daemon a little smaller and easier to understand.

   * A lot of small bug fixes done.

   * New INSTALL files (not final version) and some info regarding
     porting.

Changes in release 3.19.x
=========================

Changes in release 3.19.5
-------------------------

   * Some new functions, some more optimisation on joins.

   * Should now compile clean on Linux (2.0.x)

   * Added functions DATABASE(),USER(),POW(),LOG10() (needed for ODBC).

   * In a WHERE with a ORDER BY on fields from only one table the table
     is now preferred as first table in a multi-join.

   * HAVING and IS NULL or IS NOT NULL now works.

   * A group on one column and a sort on a group function (SUM,AVG...)
     didn't work together. Fixed.

   * mysqldump: Didn't send password to server.

Changes in release 3.19.4
-------------------------

   * Fixed horrible locking bug when inserting in one thread and reading
     on another thread.

   * Fixed one-off decimal bug.  1.00 was output as 1.0

   * Added attribute 'Locked' to process list as info if a query is
     locked by another query.

   * Fixed full magic timestamp. Timestamp length may now be
     14,12,10,8,6,4 or 2.

   * sort on some number functions could be sorted wrong on last number.

   * if(arg,syntax_error,syntax_error) crashed.

   * added functions ceiling() and round(), exp(), log() and sqrt()

   * enchanted BETWEEN to handle strings.

Changes in release 3.19.3
-------------------------

   * Fixed that select with grouping on blob's doesn't return wrong blob
     info. grouping, sorting and distinct on blobs will not yet work as
     expected (Probably it will group/sort by the first 7 characters in
     the blob). Groping on formulas with a fixed string size (use mid
     on blob) should work.

   * When doing a full join (no direct keys) on multiple tables with
     blob fields, the blob was garbage on output.

   * Fixed distinct with calculated columns.

Known errors and design deficiencies in *MySQL*
***********************************************

   * You can not build in another directory when using MIT-pthreads.
     Since this requires changes to MIT-pthreads we are not likely to
     fix this.

   * HAVING can only use fields in select expression list. Functions
     must be aliased. You must use

          SELECT grp,COUNT(*) as c FROM table GROUP BY grp HAVING c > 1
          
          instead of
          
          SELECT grp FROM table GROUP BY grp HAVING count(*) > 1

   * Blobs can't 'reliably' be used in `GROUP BY' or `ORDER BY' or
     `DISTINCT'. Only the first `max_sort_length' (default 1024) are
     used when comparing blobs in these cases.  This can be changed with
     the `-O max_sort_length' parameter to mysql. A workaround for most
     cases is to use a substring: `SELECT DISTINCT LEFT(blob,2048) FROM
     table'.

   * Calculation is done with `bigint' or `double' (both are normally
     64 bit long). It depends on the function which precision one gets.
     The general rule is that bit functions are done with bigint
     precision, IF, and ELT() with bigint or double precision and the
     rest with double precision.  One should try to avoid using bigger
     unsigned long long values than 63 bits (9223372036854775807) for
     anything else than bit fields!

   * All field types are fixed point fields. That means one must
     specify how many decimals a floating point field shall have. All
     results will be returned with the correct number of decimals.

   * All string columns, except BLOBS, have automatically all end spaces
     removed when retrieved. For CHAR types this is ok may be regarded
     as a feature according to ANSI SQL92. The bug is that VARCHAR
     columns are treated the same way.

   * One can only have up to 255 enum and set columns in one table.

   * Updates that updates a key with a where on the same key may fail
     because the key is used to search records and will be found
     multiple times:

     UPDATE SET KEY=KEY+1 WHERE KEY > 100

     This will be fixed by not using keys that contains fields that are
     going to be updated.

   * safe_mysqld re-directs all messages from mysqld to the mysqld log.
     One problem with this is that if you do 'mysqladmin refresh' to
     close and reopen the log stdout and stderr is still redirected to
     the old log.  If you use -log extensively, you should edit
     safe_mysqld to log to 'hostname'.err instead of 'hostname'.log so
     you can easily reclaim the space for the old log by deleting the
     old one and doing a 'refresh'.

   For platform specific bugs see the sections about compiling and
porting.

List of things we want to add to *MySQL* in the future (The TODO).
******************************************************************

   Everything in this list is in the order it will be done.  If you
want to affect the priority order, please register a licence or support
us and tell us what you want to have done more quickly. *Note Licensing
and Support::.

Things what has to be done in the real near future
==================================================

   * Delayed inserts for log tables.

   * Optimized MIN(key) and MAX(key). Needed for sub select.

   * Subqueries. 'select id from t where grp in (select grp from g
     where u > 100)'

   * Optimize some queries to only use keys.

   * FreeBSD and MIT-pthreads;  Do sleeping threads take CPU?

   * Allow join on key parts (optimizing issue).

   * Fix that temporary HEAP tables is automatically converted to NISAM
     if they get too big. At the moment one gets 'error 135' or 'Table
     xxx is full' if one does a query which has to use a big temporary
     table.

   * Allow one to store *MySQL* server and client startup options in
     global and user files.

   * Add DISTINCT qualifier to COUNT(), SUM()...

   * Binary portable data tables (a new version of ISAM)

   * Change conv_blob to handle blob as a text field.

   * Entry for DECRYPT() and ENCRYPT()

   * Remember FOREIGN key definitions in the .frm file.

   * Don't add automatic DEFAULT values to columns.  Give an error when
     using an INSERT that doesn't contain a column that doesn't have an
     DEFAULT.

   * Caching of queries and results. This should be done as a separated
     module that examines each query and if this is query is in the
     cache the cached result should be returned.  When one updates a
     table one should remove as few queries as possible from the cache.
     This should give a big speed bost on machines with much ram where
     queries are often repeated (like www applications).  One idea
     would be to only cache queries of type: SELECT CACHED ....

   * Fix libmysql.c to allow two mysql_query() commands in a row without
     reading results or give a nice error message when one does this.

   * Optimize BIT type to take 1 bit (now BIT takes 1 char).

   * Check why MIT-pthreads ctime() doesn't work on some FreeBSD
     systems.

   * Check if locked threads take any cpu.

   * Add ORDER BY to update. This would be handy with functions like:
     generate_id(start,step).

   * Add a IMAGE option to LOAD DATA INFILE to not update timestamps
     and auto increment fields.

   * Demo procedure: analyze

   * HAVING + group functions without alias: select name from company
     group by name having count(*) > 1

   * Automatic output from 'mysql' to netscape.

   * LOCK DATABASES. (with various options)

   * NATURAL JOIN

   * Change sort to alloc memory in 'hunks' to get better memory
     utilisation.

   * DECIMAL and NUMERIC types can't read exponential numbers; One must
     recode Field_decimal::store(const char *from,uint len) to fix this.

   * Add ANSI SQL EXTRACT function.

   * Add functions: MAKE_SET(set_bits,'aaa,bbb,ccc,ddd,eee") -> Returns
     a set string.  MAKE_SET(1 | 8, 'aaa,bbb,ccc,ddd,eee")   ->
     'aaa,ddd'

     EXPORT_SET(set_column,'Y','N',[separator],[number_of_set_values])

     where separator is ',' as default and number_of_set_values is taken
     from the set_column (or is 64 if set_column is an expression)

     EXPORT_SET(9,'Y','N',',',5) -> Y,N,N,Y,N

   * Add use of 't1 JOIN t2 ON ...' and 't1 JOIN t2 USING ...'.
     Currently one can only use this syntax with LEFT JOIN.

   * Add full support for unsigned long long type.

   * A LOCK DATABASE function (for backup's)

   * Function CASE

   * Much more variables for 'show status'.  Counts for:
     insert/delete/updates statements. records reads and updated.
     Selects on 1 table and selects with joins.  Mean number of tables
     in select. key buffer read/write hits (logical and real).  order
     by, group by, temporary tables created.

   * If one aborts a 'mysql' in the middle of a query, one should open
     another connection and kill the old running query'.  Alternatively
     one should try to detect this in the server.

   * Add a handler interface for table information so one can use it as
     a system table. This would be a bit slow if one requested
     information about all tables, but very flexible.  One should also
     implement 'show info from table' for basic table information.

Things that have to be done sometime
====================================

   * Implement a table optimiser by a analyze procedure call that
     returns a table like show fields with min and max value and the
     best *MySQL* type for that expression.

   * Implement function: get_changed_tables(timeout,table1,table2,...)
     Implement function: LAST_UPDATED(table_name)

   * Atomic updates; This includes a language that one can even use for
     a set of stored procedures.

   * update items,month set items.price=month.price where
     items.id=month.id;

   * Change reading through tables to use memmap when possible. Now only
     compressed tables use memmap.

   * Make a SQL standard GRANT command with *MySQL* extensions.

   * Add a new privilege 'Show_priv' for 'SHOW' commands.

   * Make the automatic timestamp code nicer.  Add timestamps to the
     update log with SET TIMESTAMP=#;

   * Optimize the autoincrement code.

   * Use read/write mutex in some places to get more speed.

   * Full foreign key support. One probably wants to implement a
     procedural language first.

   * Simple views (first on one table, later on any expression).

   * Automatic close some tables if a table, temporary table or
     temporary files gets error 23 (Not enough open files).

   * When one finds a field=#, change all occurrence of field to #.
     Now this is only done for some simple cases.

   * Change all const expression with calculated expressions if
     possible.

   * Optimize key = expression. At the moment only key = field or key =
     constant are optimised.

   * Join some of the copy functions for nicer code.

   * Change sql_yacc.y to an inline parser to get down it's size and get
     better error messages (5 days)

   * Change the parser to use only one rule per different number of
     arguments in function.

   * Use of full calculation names in the order part. (For ACCESS97)

   * UNION and FULL OUTER JOIN. (Currently only LEFT OUTER JOIN is
     supported)

   * Allow UNIQUE on fields that can be NULL.

   * SQL_OPTION MAX_SELECT_TIME=#to put a time limit on a query.

   * Make the update log to a database.

   * Negative LIMIT to retrieve data from the end.

   * Alarm round client connect/read/write functions.

   * Make a mysqld version which isn't multithreaded (3-5 days).

   * Please note the changes to safe_mysqld: according to FSSTND (which
     Debian tries to follow) PID files should go into
     /var/run/<progname>.pid and log files into /var/log. It would be
     nice if you could put the "DATADIR" in the first declaration of
     "pidfile" and "log", so the placement of these files can be
     changed with a single statement.

   * Add '-drop' command to mysqldump to start output with a drop of
     all tables.

   * Better dynamic record layout to avoid fragmentation.

   * UPDATE SET blob=read_blob_from_file('my_gif') where id=1;

   * Allow sorting on RAND():

     SELECT email,RAND() AS ran FROM info ORDER BY ran;

   * Allow a client to request logging.

   * insert into bar (yobabyyo) values (1),(2),(3);

   * Add use of zlib() for gziped files to LOAD DATA INFILE.

   * Fix sorting and grouping of blobs (partly solved now).

   * Stored procedures.  This is currently not regarded to be very
     important as stored procedures are not very standardized yet.
     Another problem is that true stored procedures makes it much
     harder for the optimizer and in many cases the result is slower
     than before We will on the other hand add a simple atomic) update
     language that can be used to write loops and such in the *MySQL*
     server.

   * Change to use semaphores when counting threads.  One should first
     implement a semaphore library to MIT-pthreads.

   Time is given according to amount of work, not real time. TcX's main
business is the use of *MySQL* not the development of it. But since TcX
is a very flexible company and we have put a lot of resources into the
development of *MySQL*.

Some things we don't have any plans to do
=========================================

   * Transactions with rollback (we mainly do selects, and because we
     don't do transactions we can be much quicker on everything else).
     We will support some kind of atomic operations on multiple tables
     though. Currently atomic operations can be done with `LOCK
     TABLES'/`UNLOCK TABLES' but we will make this more automatic in the
     future.

Comments on porting to other systems.
*************************************

   A working Posix thread library is needed for the server. On Solaris
2.5 we use SUN PThreads (the native thread support in 2.4 and earlier
versions are not good enough) and on Linux we use LinuxThreads by Xavier
Leroy <Xavier.Leroy@inria.fr>.

   The hard part of porting to a new UNIX variant without good native
thread support is probably to port MIT-pthreads. See
`mit-pthreads/README' and Programming POSIX Threads (http://www.humanfactor.com/pthreads/).

   The *MySQL* distribution includes a patched version of Provenzano's
Pthreads from MIT (see
MIT Pthreads web page (http://www.mit.edu:8001/people/proven/pthreads.html)). This can be used for some operating systems that does not have
posix threads.

   It is also possible to use another user level thread package named
FSU Pthreads (see
FSU pthread home page (http://www.informatik.hu-berlin.de/~mueller/pthreads.html)). This implementation is being used for the SCO port.

   See the `thr_lock.c' and `thr_alarm.c' programs in the mysys
directory for some tests/examples of these problems

   Both the server and the client needs a working C++ compiler (we use
gcc and have tried SparcWorks). Other compiler that is known to work is
the IRIX cc.

   To compile only the client use `./configure --without-server'

   There currently no support for only compiling the server. Nor is it
likly to be added unless someone has a good reason for it.

   If you want/need to change any Makefile or the configure script you
must get automake and autoconf. We have used autoconf-2.12 and
automake-1.2.

   All steps needed to remake everything from the most basic files.

     /bin/rm */.deps/*.P
     /bin/rm -f config.cache
     aclocal
     autoheader
     aclocal
     automake
     autoconf
     ./configure --with-debug=yes --prefix='your installation directory'
     
     # The makefiles generated above needs GNU make (called gmake below)
     gmake clean all install init-db

   If you run into problem with a new port, you may have to do some
debugging of mysql!  *Note Debugging::

   *NOTE*: Before you start debugging mysqld, first get the test
programs mysys/thr_alarm and mysys/thr_lock to work.  This will ensure
that your thread installation has even a remotely change to work!

Debugging *MySQL*
=================

   If you have some very specific problem, you can always try to debug
*MySQL*.  To do this you must configure *MySQL* with the option
`--with-debug=yes'.  You can check if *MySQL* if compiled with
debugging by doing: `mysqld --help'.  If the `--debug' flag is listed
with the options then you have debugging enabled.  `mysqladmin ver'
also lists the mysqld version as `mysql ... -debug' in this case.

   Start the mysql server with a trace log in /tmp/mysql.trace. The log
file will get very *BIG*.

   `mysqld --debug'

   or you can start it with

   `mysqld --debug=d,info,error,query,general,where:O,/tmp/mysql.trace'

   which only prints information with the most interesting tags.

   When you configure *MySQL* for debugging you automatically enable a
lot of extra safety check functions that monitor the health of mysqld.
If they find something 'unexpected' a entry will be written to stderr,
which safe_mysqld directs to the error log!  This also means that if
you are having some unexpected problems with `MySQL', the first thing
you, if you are using a source distribution, is to configure `MySQL' for
debugging!  (The second thing is of course to mail to mysql@tcx.se and
ask for help.  Please use the mysqlbug script for all bug reports or
questions regarding a `MySQL' version you are using!

   On most system (except Linux) you can also start mysqld in `gdb' to
get more information if mysqld crashes.

     shell> gdb libexec/mysqld
     gdb>   run
     ...
     back   # Do this when mysqld crashes
     quit

Comments about RTS threads
==========================

   I have tried to use the RTS thread packages with *MySQL* but
stumbled on the following problems:

   They use old version of a lot of POSIX calls and it is very tedious
to make wrappers for all functions. I am inclined to think that it would
be easier to change the thread libraries to the newest POSIX
specification.

   Some wrappers are already written. Se mysys/my_pthread.c for more
info.

   At least the following should be changed:

   pthread_get_specific should use on argument.  sigwait should take
two arguments.  A lot of functions (at least pthread_cond_wait,
pthread_cond_timedwait) should return the error code on error. Now they
return -1 and set errno.

   Another problem is that user level threads uses the ALRM signal and
this aborts a lot of functions (read, write, open...). *MySQL* should
do a retry on interrupt on all of these but it not that easy to verify
it.

   The biggest unsolved problem is the following:

   To get thread_level alarms I changed mysys/thr_alarm.c to wait
between alarms with pthread_cond_timedwait() but this aborts with error
EINTR.  I tried to debug the thread library why this happens but
couldn't find any easy solution.

   If someone wants to try *MySQL* with RTS threads I suggest the
following:

   * Change functions *MySQL* uses from the thread library to POSIX.
     This shouldn't take that long.

   * Compile all libraries with the -DHAVE_rts_threads.

   * Compile thr_alarm

   * If there is some small differences in the implementation they may
     be fixed by changing my_pthread.h and my_pthread.c

   * Run thr_alarm. If it runs without any 'warning', 'error' or
     aborted messages you are one the right track. Here follows an
     successful run on Solaris:
          Main thread: 1
          Tread 0 (5) started
          Thread: 5  Waiting
          process_alarm
          Tread 1 (6) started
          Thread: 6  Waiting
          process_alarm
          process_alarm
          thread_alarm
          Thread: 6  Sleeped for 1 (1) sec
          Thread: 6  Waiting
          process_alarm
          process_alarm
          thread_alarm
          Thread: 6  Sleeped for 2 (2) sec
          Thread: 6  Simulation of no alarm needed
          Thread: 6  Sleeped for 0 (3) sec
          Thread: 6  Waiting
          process_alarm
          process_alarm
          thread_alarm
          Thread: 6  Sleeped for 4 (4) sec
          Thread: 6  Waiting
          process_alarm
          thread_alarm
          Thread: 5  Sleeped for 10 (10) sec
          Thread: 5  Waiting
          process_alarm
          process_alarm
          thread_alarm
          Thread: 6  Sleeped for 5 (5) sec
          Thread: 6  Waiting
          process_alarm
          process_alarm
          
          ...
          thread_alarm
          Thread: 5  Sleeped for 0 (1) sec
          end

What is the difference between different thread packages?
=========================================================

   *MySQL* is very dependent on the used thread package. So when
choosing a good platform for *MySQL* the thread package is very
important.

   There are at least three types of thread packages.

   * User threads in a single process. Thread switching is managed with
     alarms and the threads library manages all not thread- safe
     functions with locks. Read, write and select are usually managed
     with a thread-specific select that switches to another thread if
     the running threads have to wait for data.  If the user thread
     packages are integrated in the standard libs (FreeBSD and BSDI
     threads) the thread package requires less overhead than thread
     packages that have to map all unsafe calls (MIT-pthreads,
     FSU-threads and RTS threads).  In some environments (for example
     SCO), all system calls are thread- safe so the mapping can be done
     very easily (FSU-threads on SCO).  Downside: All mapped calls take
     a little time and it's quite tricky to be able to handle all
     situations. There are usually also some system calls that are not
     handled by the thread package (like MIT-pthreads and sockets).
     Thread scheduling isn't always optimal.

   * User threads in separate processes. Thread switching is done by the
     kernel and all data is shared between threads.  The thread package
     manages the standard thread calls to allow sharing data between
     threads.  LinuxThreads is using this method.  Downside: Lots of
     processes. Thread creating is slow. If one thread dies the rest
     are usually left hanging and one has to kill them all before
     restarting. Thread switching is somewhat expensive.

   * Kernel threads. Thread switching is handled by the thread library
     or the kernel and is very fast. Everything is done in one process
     but 'ps' may on some systems show the different threads. If one
     thread aborts the whole process aborts. Most system calls are
     threadsafe and should require very little overhead.  Solaris,
     HP-UX, AIX and OSF1 has kernel threads.

   In some systems kernel threads are managed by integrating user level
threads in the system libraries. In such cases, the thread switching
can only be done by the thread library and the kernel isn't really
'thread aware'.

Description of *MySQL* regular expression syntax.
*************************************************

   Regular expressions are a powerful way of specifying complex
searches.

   *MySQL* uses regular Henry Spencers inplementation of regular
expressions. And that is aimed to conform to POSIX 1003.2. *MySQL* uses
the extended version.

   To get more exact information see Henry Spencers regex.7 manual that
is included in the source distribution. *Note Credits::.

   This is a simplistic reference that skips the details. From here on a
regualr expressions is called a regexp.

   A regular expression describes a set of strings. The simplest case is
one that has no special characters in it. For example the regexp
`hello' matches `hello' and nothing else.

   Nontrivial regular expressions use certain special constructs so that
they can match more than one string. For example, the regexp
`hello|word' matches either the string `hello' or the string `word'.

   And a more comples example regexp `B[an]*s' matches any of the
strings `Bananas', `Baaaaas', `Bs' and all other string starting with a
`B' and continuing with any number of `a' `n' and ending with a `s'.

   The following special characters/constructs are known.
`^'
     Start of whole string.
          mysql> select "fo\nfo" regexp "^fo$";           -> 0
          mysql> select "fofo" regexp "^fo";              -> 1

`$'
     End of whole string.
          mysql> select "fo\no" regexp "^fo\no$";         -> 1
          mysql> select "fo\no" regexp "^fo$";            -> 0

`.'
     Any character (including newline).
          mysql> select "fofo" regexp "^f.*";             -> 1
          mysql> select "fo\nfo" regexp "^f.*";           -> 1

`a*'
     Any sequence of zero or more a's.
          mysql> select "Ban" regexp "^Ba*n";             -> 1
          mysql> select "Baaan" regexp "^Ba*n";           -> 1
          mysql> select "Bn" regexp "^Ba*n";              -> 1

`a+'
     Any sequence of one or more a's.
          mysql> select "Ban" regexp "^Ba+n";             -> 1
          mysql> select "Bn" regexp "^Ba+n";              -> 0

`a?'
     Either zero or one a.
          mysql> select "Bn" regexp "^Ba?n";              -> 1
          mysql> select "Ban" regexp "^Ba?n";             -> 1
          mysql> select "Baan" regexp "^Ba?n";            -> 0

`de|abc'
     Either the sequence `de' or `abc'.
          mysql> select "pi" regexp "pi|apa";             -> 1
          mysql> select "axe" regexp "pi|apa";            -> 0
          mysql> select "apa" regexp "pi|apa";            -> 1
          mysql> select "apa" regexp "^(pi|apa)$";        -> 1
          mysql> select "pi" regexp "^(pi|apa)$";         -> 1
          mysql> select "pix" regexp "^(pi|apa)$";        -> 0

`(abc)*'
     Zero or more times the sequence `abc'.
          mysql> select "pi" regexp "^(pi)+$";            -> 1
          mysql> select "pip" regexp "^(pi)+$";           -> 0
          mysql> select "pipi" regexp "^(pi)+$";          -> 1

`{1}'
`{2,3}'
     The is a more general way of writing regexps that match many
     occurences.
    `a*'
          Can be written as `a{0,}'.

    `+'
          Can be written as `a{1,}'.

    `?'
          Can be written as `a{0,1}'.  To be more precice an atom
     followed by a bound containing one integer `i' and no comma
     matches a sequence of exactly `i' matches of the atom. An atom
     followed by a bound containing one integer `i' and a comma matches
     a sequence of `i' or more matches of the atom.  An atom followed
     by a bound containing two integers `i' and `j' matches a sequence
     of `i' through `j' (inclusive) matches of the atom.

     Both arguments must `0 >= value <= RE_DUP_MAX (default 255)', and
     if there are two of them, the second must be bigger or equal to the
     first.

`[a-dX]'
`[^a-dX]'
     Any character which is (not if ^ is used) either `a', `b', `c',
     `d' or `X'. To include `]' it has to be written first. To include
     `-' it has to be written first or last. So `[0-9]' matches any
     decimal digit. All character that does not have a defined mening
     inside a `[]' pair has no special meaning and matches only itself.
          mysql> select "aXbc" regexp "[a-dXYZ]";         -> 1
          mysql> select "aXbc" regexp "^[a-dXYZ]$";       -> 0
          mysql> select "aXbc" regexp "^[a-dXYZ]+$";      -> 1
          mysql> select "aXbc" regexp "^[^a-dXYZ]+$";     -> 0
          mysql> select "gheis" regexp "^[^a-dXYZ]+$";    -> 1
          mysql> select "gheisa" regexp "^[^a-dXYZ]+$";   -> 0

`[[.characters.]]'
     The sequence of characters of that collating element. The sequence
     is a single element of the bracket expression's list. A bracket
     expression containing a multi-character collating element can thus
     match more than one character, e.g. if the collating sequence
     includes a `ch' collating element, then the RE `[[.ch.]]*c'
     matches the first five characters of `chchcc'.

`[=character-class=]'
     An equivalence class, standing for the sequences of characters of
     all collating elements equivalent to that one, including itself.

     For example, if `o' and `(+)' are the members of an equivalence
     class, then `[[=o=]]', `[[=(+)=]]', and `[o(+)]' are all
     synonymous. An equivalence class may not be an endpoint of a range.

`[:character_class:]'
     Within a bracket expression, the name of a character class
     enclosed in `[:' and `:]' stands for the list of all characters
     belonging to that class. Standard character class names are:

     alnum                  digit                  punct                  
     alpha                  graph                  space                  
     blank                  lower                  upper                  
     cntrl                  print                  xdigit                 

     These stand for the character classes defined in ctype(3). A
     locale may provide others. A character class may not be used as an
     endpoint of a range.
          mysql> select "justalnums" regexp "[[:alnum:]]+";       -> 1
          mysql> select "!!" regexp "[[:alnum:]]+";               -> 0

`[[:<:]]'
`[[:>:]]'
     These match the null string at the beginning and end of a word
     respectively.  A word is defined as a sequence of word characters
     which is neither preceded nor followed by word characters. A word
     character is an alnum character (as defined by ctype(3)) or an
     underscore.
          mysql> select "a word a" regexp "[[:<:]]word[[:>:]]";      -> 1
          mysql> select "a xword a" regexp "[[:<:]]word[[:>:]]";     -> 0

     mysql> select "weeknights" regexp "^(wee|week)(knights|nights)$"; -> 1

What is UNIREG?
***************

   Unireg is our tty interface builder, but it uses a low level
connection to our NISAM (which is used by *MySQL*) and because of this
it is very quick. It has existed since 1979 (on Unix in C since ~1986).

   Unireg has the following components:

   * One table viewer with updates/browsing.

   * Multi table viewer (with one scrolling region).

   * Table creator. (With lots of column tags you can't create with
     *MySQL*) This is WYSIWYG (for a tty). You design a screen and
     Unireg prompts for the column specification.

   * Report generator.

   * A lot of utilities (Quick export/import of tables to/from text
     files, analysis of table contents...).

   * Powerful multi-table updates (which we use a lot) with a BASIC like
     language with LOTS of functions.

   * Dynamic languages (at present in Swedish and Finnish). If somebody
     wants an English version there are a few files that would have to
     be translated.

   * The ability to run updates interactively or in a batch.

   * Emacs like key definitions with keyboard macros.

   * All this in a binary of 800k.

   * The convform utility. Changes .frm and text files between different
     character sets.

   * The pack_isam utility. Packs a NISAM table (makes it 50-80%
     smaller). The table can be read by *MySQL* like an ordinary table.
     Only one record has to be decompressed / access. Cannot handle
     BLOB:s or updates (yet).

   We update most of our production databases with the UNIREG interface
and serve web pages through *MySQL* (and in some extreme cases the
UNIREG report generator).

   Unireg takes about 3M of disk space and works on at least the
following platforms: SUN OS 4.x, Solaris, Linux, HP-UX, ICL Unix, DNIX,
SCO and MSDOS.

   Unireg is currently only available in Swedish and Finnish.

   The price tag for UNIREG is 10,000 Swedish kr (about 1500$ US), but
this includes support. UNIREG is distributed as a binary. (But all the
ISAM sources can be found in *MySQL*). Usually we compile the binary
for the customer at their site.

   All new development is concentrated to *MySQL*.

The *MySQL* server license
**************************

                      *MySQL FREE PUBLIC LICENSE*

                      (Version 4, March 5, 1995)

    Copyright (C) 1995, 1996 TcX AB & Monty Program KB & Detron HB

       Stockholm SWEDEN, Helsingfors FINLAND and Uppsala SWEDEN

                         All rights reserved.

   NOTE: This license is not the same as any of the GNU Licenses
published by the Free Software Foundation. Its terms are substantially
different from those of the GNU Licenses. If you are familiar with the
GNU Licenses, please read this license with extra care.

   This License applies to the computer program known as "MySQL".  The
"Program", below, refers to such program, and a "work based on the
Program" means either the Program or any derivative work of the Program,
as defined in the United States Copyright Act of 1976, such as a
translation or a modification. The Program is a copyrighted work whose
copyright is held by TcX Datakonsult AB and Monty Program KB and Detron
HB.

   This License does not apply when running "MySQL" on any Microsoft
operating system. Microsoft operating systems include all versions of
Microsoft Windows NT and Microsoft Windows.

   BY MODIFYING OR DISTRIBUTING THE PROGRAM (OR ANY WORK BASED ON THE
PROGRAM), YOU INDICATE YOUR ACCEPTANCE OF THIS LICENSE TO DO SO, AND ALL
ITS TERMS AND CONDITIONS FOR COPYING, DISTRIBUTING OR MODIFYING THE
PROGRAM OR WORKS BASED ON IT. NOTHING OTHER THAN THIS LICENSE GRANTS
YOU PERMISSION TO MODIFY OR DISTRIBUTE THE PROGRAM OR ITS DERIVATIVE
WORKS. THESE ACTIONS ARE PROHIBITED BY LAW. IF YOU DO NOT ACCEPT THESE
TERMS AND CONDITIONS, DO NOT MODIFY OR DISTRIBUTE THE PROGRAM.

  1. Licenses.

     Licensor hereby grants you the following rights, provided that you
     comply with all of the restrictions set forth in this License and
     provided, further, that you distribute an unmodified copy of this
     License with the Program:

       a. You may copy and distribute literal (i.e., verbatim) copies
          of the Program's source code as you receive it throughout the
          world, in any medium.

       b. You may modify the Program, create works based on the Program
          and distribute copies of such throughout the world, in any
          medium.

  2. Restrictions.

     This license is subject to the following restrictions:
       a. Distribution of the Program or any work based on the Program
          by a commercial organization to any third party is prohibited
          if any payment is made in connection with such distribution,
          whether directly (as in payment for a copy of the Program) or
          indirectly (as in payment for some service related to the
          Program, or payment for some product or service that includes
          a copy of the Program "without charge"; these are only
          examples, and not an exhaustive enumeration of prohibited
          activities). However, the following methods of distribution
          involving payment shall not in and of themselves be a
          violation of this restriction:

            A. Posting the Program on a public access information
               storage and retrieval service for which a fee is
               received for retrieving information (such as an on-line
               service), provided that the fee is not content-dependent
               (i.e., the fee would be the same for retrieving the same
               volume of information consisting of random data).

            B. Distributing the Program on a CD-ROM, provided that the
               files containing the Program are reproduced entirely and
               verbatim on such CD-ROM, and provided further that all
               information on such CD-ROM be redistributable for
               non-commercial purposes without charge.

       b. Activities other than copying, distribution and modification
          of the Program are not subject to this License and they are
          outside its scope.  Functional use (running) of the Program
          is not restricted, and any output produced through the use of
          the Program is subject to this license only if its contents
          constitute a work based on the Program (independent of having
          been made by running the Program).

       c. You must meet all of the following conditions with respect to
          the distribution of any work based on the Program:
            A. If you have modified the Program, you must cause your
               work to carry prominent notices stating that you have
               modified the Program's files and the date of any change;

            B. You must cause any work that you distribute or publish,
               that in whole or in part contains or is derived from the
               Program or any part thereof, to be licensed as a whole
               and at no charge to all third parties under the terms of
               this License;

            C. If the modified program normally reads commands
               interactively when run, you must cause it, at each time
               the modified program commences operation, to print or
               display an announcement including an appropriate
               copyright notice and a notice that there is no warranty
               (or else, saying that you provide a warranty). Such
               notice must also state that users may redistribute the
               Program only under the conditions of this License and
               tell the user how to view the copy of this License
               included with the Program. (Exception: if the Program
               itself is interactive but does not normally print such
               an announcement, your work based on the Program is not
               required to print an announcement.);

            D. You must accompany any such work based on the Program
               with the complete corresponding machine-readable source
               code, delivered on a medium customarily used for
               software interchange. The source code for a work means
               the preferred form of the work for making modifications
               to it.  For an executable work, complete source code
               means all the source code for all modules it contains,
               plus any associated interface definition files, plus the
               scripts used to control compilation and installation of
               the executable code. However, the source code
               distributed need not include anything that is normally
               distributed (in either source or binary form) with the
               major components (compiler, kernel, and so on) of the
               operating system on which the executable runs, unless
               that component itself accompanies the executable code;

            E. If you distribute any written or printed material at all
               with the Program or any work based on the Program, such
               material must include either a written copy of this
               License, or a prominent written indication that the
               Program or the work based on the Program is covered by
               this License and written instructions for printing
               and/or displaying the copy of the License on the
               distribution medium;

            F. You may not impose any further restrictions on the
               recipient's exercise of the rights granted herein.

               If distribution of executable or object code is made by
               offering the equivalent ability to copy from a
               designated place, then offering equivalent ability to
               copy the source code from the same place counts as
               distribution of the source code, even though third
               parties are not compelled to copy the source code along
               with the object code.

  3. Reservation of Rights.

     No rights are granted to the Program except as expressly set forth
     herein. You may not copy, modify, sublicense, or distribute the
     Program except as expressly provided under this License. Any
     attempt otherwise to copy, modify, sublicense or distribute the
     Program is void, and will automatically terminate your rights
     under this License. However, parties who have received copies, or
     rights, from you under this License will not have their licenses
     terminated so long as such parties remain in full compliance.

  4. Other Restrictions.

     If the distribution and/or use of the Program is restricted in
     certain countries for any reason, Licensor may add an explicit
     geographical distribution limitation excluding those countries, so
     that distribution is permitted only in or among countries not thus
     excluded. In such case, this License incorporates the limitation
     as if written in the body of this License.

  5. Limitations.

     THE PROGRAM IS PROVIDED TO YOU "AS IS," WITHOUT WARRANTY. THERE IS
     NO WARRANTY FOR THE PROGRAM, EITHER EXPRESSED OR IMPLIED,
     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE AND
     NONINFRINGEMENT OF THIRD PARTY RIGHTS. THE ENTIRE RISK AS TO THE
     QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
     PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
     SERVICING, REPAIR OR CORRECTION.

     IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
     WRITING WILL LICENSOR, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
     REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR
     DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR
     CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
     THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA
     BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
     PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
     PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF
     THE POSSIBILITY OF SUCH DAMAGES.

SQL command, type and function index.
*************************************

* Menu:

* !:                                     Logical functions.
* !=:                                    Comparison functions.
* %:                                     Mathematical functions.
* &:                                     Bit functions.
* &&:                                    Logical functions.
* (:                                     Grouping functions.
* ):                                     Grouping functions.
* *:                                     Arithmetic functions.
* +:                                     Arithmetic functions.
* - <1>:                                 Mathematical functions.
* -:                                     Arithmetic functions.
* /:                                     Arithmetic functions.
* <:                                     Comparison functions.
* <<:                                    Bit functions.
* <=:                                    Comparison functions.
* <>:                                    Comparison functions.
* =:                                     Comparison functions.
* >:                                     Comparison functions.
* >=:                                    Comparison functions.
* A BETWEEN B AND C:                     Comparison functions.
* ABS():                                 Mathematical functions.
* ACOS(X):                               Mathematical functions.
* ALTER TABLE:                           Create table.
* AND:                                   Logical functions.
* Aritmetic functions:                   Arithmetic functions.
* ASCII(S):                              String functions.
* ASIN(X):                               Mathematical functions.
* ATAN(X):                               Mathematical functions.
* ATAN2(X,Y):                            Mathematical functions.
* AVG(expr):                             Group by functions.
* BIGINT:                                Column types.
* BIN(N):                                String functions.
* Bit functions:                         Arithmetic functions.
* BIT_AND(expr):                         Group by functions.
* BIT_COUNT():                           Bit functions.
* BIT_OR(expr):                          Group by functions.
* BLOB:                                  Column types.
* BLOB (Generic):                        Type details.
* CEILING():                             Mathematical functions.
* CHAR:                                  Column types.
* CHAR(X,...):                           String functions.
* CHAR_LENGTH(S):                        String functions.
* CHARACTER_LENGTH(S):                   String functions.
* ChopBlanks:                            Perl DBI Class.
* Comment syntax:                        Drop Index.
* Comparison operators:                  Logical functions.
* CONCAT(X,Y...):                        String functions.
* connect:                               Perl DBI Class.
* Control flow functions:                String comparison functions.
* CONV(NUMBER,FROM_BASE,TO_BASE):        String functions.
* COS(X):                                Mathematical functions.
* COT(N):                                Mathematical functions.
* COUNT(Expr):                           Group by functions.
* CREATE DATABASE:                       Group by functions.
* CREATE FUNCTION:                       Comments.
* CREATE INDEX:                          Grant.
* CREATE TABLE:                          Drop database.
* CURDATE():                             Date and time functions.
* CURRENT_DATE:                          Date and time functions.
* CURRENT_TIME:                          Date and time functions.
* CURRENT_TIMESTAMP:                     Date and time functions.
* CURTIME():                             Date and time functions.
* data_sources:                          Perl DBI Class.
* DATABASE():                            Miscellaneous functions.
* DATE:                                  Column types.
* Date and time functions:               String functions.
* DATE_ADD(date, INTERVAL expr TYPE), DATE_SUB(date, INTERVAL expr TYPE): Date and time functions.
* DATE_FORMAT(Date, Format):             Date and time functions.
* DATETIME:                              Column types.
* DAYNAME(date expr):                    Date and time functions.
* DAYOFMONTH(date expr):                 Date and time functions.
* DAYOFWEEK(date expr):                  Date and time functions.
* DAYOFYEAR(date expr):                  Date and time functions.
* DECIMAL:                               Column types.
* DEGREES(N):                            Mathematical functions.
* DELETE:                                Delete table.
* DELETE TABLE:                          Alter table.
* DESC:                                  Explain.
* DESCRIBE:                              Explain.
* disconnect:                            Perl DBI Class.
* do:                                    Perl DBI Class.
* DOUBLE PRECISION:                      Column types.
* DROP DATABASE:                         Create database.
* DROP FUNCTION:                         Comments.
* DROP INDEX:                            Create Index.
* ELT(N, A1, A2, A3...):                 String functions.
* ENCRYPT(String[, Salt]):               Miscellaneous functions.
* ENUM <1>:                              Type details.
* ENUM:                                  Column types.
* execute:                               Perl DBI Class.
* EXP(N):                                Mathematical functions.
* EXPLAIN:                               Show.
* expr IN (value,...):                   String comparison functions.
* expr LIKE expr:                        String comparison functions.
* expr NOT IN (value,...):               String comparison functions.
* expr NOT LIKE expr:                    String comparison functions.
* expr NOT REGEXP expr:                  String comparison functions.
* expr REGEXP text_literal:              String comparison functions.
* expr RLIKE text_literal:               String comparison functions.
* fetchall_arrayref:                     Perl DBI Class.
* fetchrow_array:                        Perl DBI Class.
* fetchrow_arrayref:                     Perl DBI Class.
* fetchrow_hashref:                      Perl DBI Class.
* FIELD(S, S1, S2, S3...):               String functions.
* FIND_IN_SET(string,string of strings): String functions.
* finish:                                Perl DBI Class.
* FLOAT:                                 Column types.
* FLOAT(4):                              Column types.
* FLOAT(8):                              Column types.
* FLOAT(M,D):                            Column types.
* FLOOR():                               Mathematical functions.
* FORMAT(Nr, Num):                       Miscellaneous functions.
* FROM_DAYS():                           Date and time functions.
* FROM_UNIXTIME(Unix_timestamp):         Date and time functions.
* FROM_UNIXTIME(Unix_timestamp, Format_string): Date and time functions.
* GET_LOCK(String,timeout):              Miscellaneous functions.
* GRANT:                                 Set option.
* Group by functions:                    Miscellaneous functions.
* HEX(N):                                String functions.
* HOUR(time expr):                       Date and time functions.
* IF(A,B,C):                             Control flow functions.
* IFNULL(A,B):                           Control flow functions.
* INSERT:                                Join.
* INSERT(Org, Start, Length, New):       String functions.
* insertid:                              Perl DBI Class.
* INSTR(A,B):                            String functions.
* INT:                                   Column types.
* INTERVAL(N, N1, N2, N3...):            String functions.
* is_blob:                               Perl DBI Class.
* is_key:                                Perl DBI Class.
* is_not_null:                           Perl DBI Class.
* is_num:                                Perl DBI Class.
* is_pri_key:                            Perl DBI Class.
* ISNULL(A):                             Comparison functions.
* JOIN:                                  Select.
* LAST_INSERT_ID():                      Miscellaneous functions.
* LCASE(A):                              String functions.
* LEFT JOIN:                             Select.
* LEFT(str,length):                      String functions.
* length:                                Perl DBI Class.
* LENGTH(S):                             String functions.
* LIKE:                                  String comparison functions.
* LOAD DATA INFILE:                      Replace.
* LOCATE(A,B):                           String functions.
* LOCATE(A,B,C):                         String functions.
* LOCK TABLES:                           Describe.
* LOG(X):                                Mathematical functions.
* LOG10(X):                              Mathematical functions.
* Logical functions:                     Bit functions.
* LONGBLOB:                              Column types.
* LONGTEXT:                              Column types.
* LOWER(A):                              String functions.
* LPAD(A,B,C):                           String functions.
* LTRIM(str):                            String functions.
* Mathematical functions:                Control flow functions.
* MAX(expr):                             Group by functions.
* MAX(X,Y...):                           Mathematical functions.
* max_length:                            Perl DBI Class.
* MEDIUMBLOB:                            Column types.
* MEDIUMINT:                             Column types.
* MEDIUMTEXT:                            Column types.
* MID(A, B, C):                          String functions.
* MIN(expr):                             Group by functions.
* MIN(X,Y...):                           Mathematical functions.
* MINUTE(time expr):                     Date and time functions.
* Miscellaneous functions:               Date and time functions.
* MOD():                                 Mathematical functions.
* MONTH(date expr):                      Date and time functions.
* MONTHNAME(date expr):                  Date and time functions.
* mysql_affected_rows:                   C.
* mysql_close:                           C.
* mysql_connect:                         C.
* mysql_create_db:                       C.
* mysql_data_seek:                       C.
* mysql_drop_db:                         C.
* mysql_eof:                             C.
* mysql_error:                           C.
* mysql_escape_string:                   C.
* mysql_fetch_field:                     C.
* mysql_fetch_lengths:                   C.
* mysql_fetch_row:                       C.
* mysql_field_seek:                      C.
* mysql_free_result:                     C.
* mysql_get_client_info:                 C.
* mysql_get_host_info:                   C.
* mysql_get_proto_info:                  C.
* mysql_get_server_info:                 C.
* mysql_insert_id:                       C.
* mysql_list_dbs:                        C.
* mysql_list_fields:                     C.
* mysql_list_processes:                  C.
* mysql_list_tables:                     C.
* mysql_num_fields:                      C.
* mysql_num_rows:                        C.
* mysql_query:                           C.
* mysql_real_query:                      C.
* mysql_reload:                          C.
* mysql_select_db:                       C.
* mysql_shutdown:                        C.
* mysql_stat:                            C.
* mysql_store_result:                    C.
* mysql_use_result:                      C.
* NAME:                                  Perl DBI Class.
* NOT:                                   Logical functions.
* NOW():                                 Date and time functions.
* NULLABLE:                              Perl DBI Class.
* NUM_OF_FIELDS:                         Perl DBI Class.
* NUMERIC:                               Column types.
* OCT(N):                                String functions.
* OCTET_LENGTH(S):                       String functions.
* OR:                                    Logical functions.
* Parenthesis:                           Grouping functions.
* PASSWORD(String):                      Miscellaneous functions.
* PERIOD_ADD(P, N):                      Date and time functions.
* PERIOD_DIFF(A, B):                     Date and time functions.
* PI():                                  Mathematical functions.
* POSITION(B IN A):                      String functions.
* POW(X,Y):                              Mathematical functions.
* POWER(X,Y):                            Mathematical functions.
* prepare:                               Perl DBI Class.
* QUARTER(date expr):                    Date and time functions.
* quote:                                 Perl DBI Class.
* RADIANS(N):                            Mathematical functions.
* RAND([X]):                             Mathematical functions.
* REAL:                                  Column types.
* RELEASE_LOCK(String):                  Miscellaneous functions.
* REPEAT(String, Count):                 String functions.
* REPLACE:                               Insert.
* REPLACE(A, B, C):                      String functions.
* REVERSE(String):                       String functions.
* RIGHT(A,B):                            String functions.
* ROUND(N):                              Mathematical functions.
* ROUND(Number,Decimals):                Mathematical functions.
* rows:                                  Perl DBI Class.
* RPAD(A,B,C):                           String functions.
* RTRIM(str):                            String functions.
* SEC_TO_TIME(Seconds):                  Date and time functions.
* SECOND(time expr):                     Date and time functions.
* SELECT:                                Delete.
* SESSION_USER():                        Miscellaneous functions.
* SET <1>:                               Type details.
* SET:                                   Column types.
* SET OPTION:                            Lock tables.
* SHOW COLUMNS:                          Update.
* SHOW DATABASES:                        Update.
* SHOW FIELDS:                           Update.
* SHOW INDEXE:                           Update.
* SHOW KEYS:                             Update.
* SHOW STATUS:                           Update.
* SHOW TABLES:                           Update.
* SHOW VARIABLES:                        Update.
* SIGN():                                Mathematical functions.
* SIN(X):                                Mathematical functions.
* SMALLINT:                              Column types.
* SOUNDEX(S):                            String functions.
* SPACE(N):                              String functions.
* sqrt(X):                               Mathematical functions.
* STD(expr):                             Group by functions.
* STDDEV(expr)  (Oracle format):         Group by functions.
* STRCMP():                              String comparison functions.
* String comparison functions:           Comparison functions.
* String functions:                      Mathematical functions.
* SUBSTRING(A FROM B FOR C):             String functions.
* SUBSTRING(A FROM B):                   String functions.
* SUBSTRING(A, B, C):                    String functions.
* SUBSTRING(A,B):                        String functions.
* SUBSTRING_INDEX(String, Delimiter, Count): String functions.
* SUM(expr):                             Group by functions.
* SYSDATE():                             Date and time functions.
* SYSTEM_USER():                         Miscellaneous functions.
* table:                                 Perl DBI Class.
* TAN(X):                                Mathematical functions.
* TEXT:                                  Column types.
* TEXT (Generic):                        Type details.
* TIME:                                  Column types.
* TIME_FORMAT(time expr, format):        Date and time functions.
* TIME_TO_SEC(Time):                     Date and time functions.
* TIMESTAMP <1>:                         Type details.
* TIMESTAMP:                             Column types.
* TINYBLOB:                              Column types.
* TINYINT:                               Column types.
* TINYTEXT:                              Column types.
* TO_DAYS(Date):                         Date and time functions.
* TRIM([[ BOTH | LEADING | TRAILING] [ A ] FROM ] B): String functions.
* TRUNCATE(Number, Decimals):            Mathematical functions.
* Types:                                 Column types.
* UCASE(A):                              String functions.
* UDF functions:                         Comments.
* UNIX_TIMESTAMP([date expression]):     Date and time functions.
* UNLOCK TABLES:                         Describe.
* UPDATE:                                Load.
* UPPER(A):                              String functions.
* USER():                                Miscellaneous functions.
* VARCHAR:                               Column types.
* VERSION:                               Miscellaneous functions.
* WEEK(date expr):                       Date and time functions.
* WEEKDAY(date expr):                    Date and time functions.
* YEAR:                                  Column types.
* YEAR(date expr):                       Date and time functions.
* |:                                     Bit functions.
* ||:                                    Logical functions.

Concept Index
*************

* Menu:

* *MySQL*:                               Introduction.
* *MySQL* binary:                        Getting it.
* *MySQL* mailing lists:                 SQL-Words.
* *MySQL* mailing lists, un/subscribing to: SQL-Words.
* *MySQL* source:                        Getting it.
* *MySQL* version <1>:                   Manual-info.
* *MySQL* version:                       Installing.
* Aritmetic expressions:                 Arithmetic functions.
* Backup:                                Replication.
* Big5 Chinese character encoding:       Using DATE.
* Bug reports:                           Asking questions.
* Case sensitivity:                      Using DATE.
* Casts:                                 Logical functions.
* Checking a table for errors:           Releases.
* Chinese:                               Using DATE.
* Choosing types:                        Type details.
* Choosing version:                      Getting it.
* Client libraries:                      Install-binary.
* Commands out of sync:                  Full table.
* Copyright:                             Contacting us.
* Cost:                                  Licensing and Support.
* default options:                       Automatic start.
* Disk full:                             Removing user.
* Downloading:                           Installing.
* Environment variables.:                Tools.
* Full disk:                             Removing user.
* Functions for select & where:          Indexes.
* General Information:                   Top.
* Getting *MySQL*:                       Installing.
* Grouping of expressions:               Functions.
* How to pronounce *MySQL*:              What-is.
* Index:                                 Grant.
* Indexes:                               Choosing types.
* isamchk:                               Programs.
* kewords:                               UDF functions.
* Keys:                                  Choosing types.
* Linking:                               Install-binary.
* make_binary_release:                   Programs.
* Manual information:                    What-is.
* Memory use:                            Compile and link options.
* msql2mysql:                            Programs.
* multi-part-index:                      Grant.
* mysql:                                 Programs.
* mysql_install_db:                      Programs.
* mysqlaccess:                           Programs.
* mysqladmin:                            Programs.
* mysqlbug:                              Programs.
* mysqld:                                Programs.
* mysqldump:                             Programs.
* mysqlimport:                           Programs.
* mysqlshow:                             Programs.
* Net etiquette <1>:                     Crashing.
* Net etiquette:                         Mailing-list.
* ODBC:                                  Adding functions.
* optimizations:                         MySQL indexes.
* Overview:                              Top.
* Pack-ISAM:                             Low-level-table-info.
* Paying:                                Support.
* Performance:                           Table size.
* Protocol mismatch:                     Upgrading-from-3.20.
* Quoting of binary data:                Base Syntax.
* Release numbers:                       Getting it.
* Release policy:                        Stability.
* replace:                               Programs.
* Replication:                           Common problems.
* Reporting errors:                      SQL-Words.
* Reserved words:                        UDF functions.
* safe_mysqld:                           Programs.
* Server functions:                      Year 2000 compliance.
* Size of tables:                        Update log.
* Stability:                             Stabilty.
* Startup parameters:                    Performance.
* Strings, How to escape things:         Syntax.
* Support:                               Cost.
* Symbolic links:                        Where optimisations.
* Table size:                            Update log.
* The table is full:                     Packet to large.
* TODO:                                  Bugs.
* Type conversions:                      Logical functions.
* Type portability:                      Indexes.
* Types, Choosing:                       Type details.
* Update log:                            Character sets.
* Version, Choosing:                     Getting it.
* Version, Latest:                       Installing.
* Which languages are supported by *MySQL*?: Server.
* Windows:                               Adding functions.
* Year 2000 compliance:                  Upgrading-to-arch.

