The MySQL (TM) software delivers a very fast, multi-threaded,
multi-user, and robust SQL (Structured Query Language)
database server.
MySQL Server is intended for mission-critical, heavy-load
production systems as well as for embedding into mass-deployed software.
MySQL is a trademark of MySQL AB.
The MySQL software is Dual Licensed. Users can choose to
use the MySQL software as an Open Source/Free Software
product under the terms of the GNU General Public License
(http://www.gnu.org/licenses/) or can purchase a standard
commercial license from MySQL AB.
See section 1.4 MySQL Support and Licensing.
The MySQL web site (http://www.mysql.com/) provides the
latest information about the MySQL software.
The following list describes some sections of particular interest in this manual:
MySQL Database Server,
see section 1.3 What Is MySQL AB?.
MySQL Database Server,
see section 1.2.2 The Main Features of MySQL.
MySQL Database Software to new architectures
or operating systems, see section E Porting to Other Systems.
MySQL Database Server,
see section 3 Tutorial Introduction.
SQL and benchmarking information, see the
benchmarking directory (`sql-bench' in the distribution).
Important:
Reports of errors (often called bugs), as well as questions and comments, should be sent to the mailing list at mysql@lists.mysql.com. See section 1.7.1.3 How to Report Bugs or Problems.
The mysqlbug script should be used to generate bug reports.
For source distributions, the mysqlbug script can be found in the
`scripts' directory. For binary distributions, mysqlbug
can be found in the `bin' directory (`/usr/bin' for the
MySQL-server RPM package).
If you have found a sensitive security bug in MySQL Server,
you should send an e-mail to security@mysql.com.
This is the MySQL reference manual; it documents MySQL
up to Version 4.0.12-Production. Functional changes are always
indicated with reference to the version, so this manual is also suitable
if you are using an older version of the MySQL software.
Being a reference manual, it does not provide general instruction on
SQL or relational database concepts.
As the MySQL Database Software is under constant development,
the manual is also updated frequently.
The most recent version of this manual is available at
http://www.mysql.com/documentation/ in many different formats,
including HTML, PDF, and Windows HLP versions.
The primary document is the Texinfo file.
The HTML version is produced automatically using a modified version of
texi2html.
The plain text and Info versions are produced with makeinfo.
The PostScript version is produced using texi2dvi and dvips.
The PDF version is produced with pdftex.
If you have a hard time finding information in the manual, you can try our searchable version at http://www.mysql.com/doc/.
If you have any suggestions concerning additions or corrections to this manual, please send them to the documentation team at docs@mysql.com.
This manual was initially written by David Axmark and Michael (Monty) Widenius. It is currently maintained by Michael (Monty) Widenius, Arjen Lentz, and Paul DuBois. For other contributors, see section C Credits.
The copyright (2003) to this manual is owned by the Swedish company
MySQL AB. See section 1.4.2 Copyrights and Licenses Used by MySQL.
This manual uses certain typographical conventions:
constant
mysqladmin works, invoke it with the
--help option.''
When commands are shown that are meant to be executed by a particular
program, the program is indicated by a prompt shown before the command. For
example, shell> indicates a command that you execute from your login
shell, and mysql> indicates a command that you execute from the
mysql client program:
shell> type a shell command here mysql> type a mysql command here
Shell commands are shown using Bourne shell syntax. If you are using a
csh-style shell, you may need to issue commands slightly differently.
For example, the sequence to set an environment variable and run a command
looks like this in Bourne shell syntax:
shell> VARNAME=value some_command
For csh, you would execute the sequence like this:
shell> setenv VARNAME value shell> some_command
Often database, table, and column names must be substituted into commands. To
indicate that such substitution is necessary, this manual uses
db_name, tbl_name and col_name. For example, you might
see a statement like this:
mysql> SELECT col_name FROM db_name.tbl_name;
This means that if you were to enter a similar statement, you would supply your own database, table, and column names, perhaps like this:
mysql> SELECT author_name FROM biblio_db.author_list;
SQL keywords are not case-sensitive and may be written in uppercase or lowercase. This manual uses uppercase.
In syntax descriptions, square brackets (`[' and `]') are used
to indicate optional words or clauses. For example, in the following
statement, IF EXISTS is optional:
DROP TABLE [IF EXISTS] tbl_name
When a syntax element consists of a number of alternatives, the alternatives are separated by vertical bars (`|'). When one member from a set of choices may be chosen, the alternatives are listed within square brackets (`[' and `]'):
TRIM([[BOTH | LEADING | TRAILING] [remstr] FROM] str)
When one member from a set of choices must be chosen, the alternatives are listed within braces (`{' and `}'):
{DESCRIBE | DESC} tbl_name {col_name | wild}
MySQL, the most popular Open Source SQL database, is
developed, distributed and supported by MySQL AB. MySQL AB is a
commercial company founded by the MySQL developers that builds its business
providing services around the MySQL database.
See section 1.3 What Is MySQL AB?.
The MySQL web site (http://www.mysql.com/)
provides the latest information about MySQL software and
MySQL AB.
MySQL is a database management system.
MySQL Server. Since computers are very good at handling large
amounts of data, database management plays a central role in computing,
as stand-alone utilities, or as parts of other applications.
SQL part of
``MySQL'' stands for ``Structured Query Language''—the
most common standardised language used to access databases.
Open Source.
Open Source means that it is possible for anyone to use and modify.
Anybody can download the MySQL software from the Internet and use it
without paying anything. Anybody so inclined can study the source code
and change it to fit their needs. The MySQL software uses the
GPL (GNU General Public License),
http://www.gnu.org/licenses/, to define what you
may and may not do with the software in different situations.
If you feel uncomfortable with the GPL or need to embed
MySQL code into a commercial application you can buy a
commercially licensed version from us.
See section 1.4.3 MySQL Licenses.
MySQL Database Server is very fast, reliable, and easy to use.
If that is what you are looking for, you should give it a try.
MySQL Server also has a practical set of features developed in
close cooperation with our users. You can find a performance comparison
of MySQL Server to some other database managers on our benchmark page.
See section 5.1.4 The MySQL Benchmark Suite.
MySQL Server was originally developed to handle large databases
much faster than existing solutions and has been successfully used in
highly demanding production environments for several years. Though
under constant development, MySQL Server today offers a rich and
useful set of functions. Its connectivity, speed, and security make
MySQL Server highly suited for accessing databases on the Internet.
MySQL Database Software is a client/server system that consists
of a multi-threaded SQL server that supports different backends,
several different client programs and libraries, administrative tools,
and a wide range of programming interfaces (APIs).
We also provide MySQL Server as a multi-threaded library which you
can link into your application to get a smaller, faster, easier-to-manage
product.
MySQL Database Server.
The official way to pronounce MySQL is ``My Ess Que Ell'' (not
``my sequel''), but we don't mind if you pronounce it as ``my sequel''
or in some other localised way.
We once started out with the intention of using mSQL to connect to our
tables using our own fast low-level (ISAM) routines. However, after some
testing we came to the conclusion that mSQL was not fast enough nor
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.
The derivation of the name MySQL is not perfectly clear. Our base
directory and a large number 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. Which of the two gave its name to MySQL is
still a mystery, even for us.
The name of the MySQL Dolphin (our logo) is Sakila, which was chosen
by the founders of MySQL AB from a huge list of names suggested by users
in the "Name the Dolphin" contest. The winning name was submitted by
Ambrose Twebaze, an open source software developer from Swaziland, Africa.
According to Ambrose, the name Sakila has its roots in SiSwati, the local
language of Swaziland. Sakila is also the name of a town in Arusha,
Tanzania, near Ambrose's country of origin, Uganda.
The following list describes some of the important characteristics
of the MySQL Database Software. See section 1.5 MySQL 4.0 In A Nutshell.
MySQL code gets tested with Purify
(a commercial memory leakage detector) as well as with Valgrind,
a GPL tool (http://developer.kde.org/~sewardj/).
FLOAT, DOUBLE, CHAR, VARCHAR,
TEXT, BLOB, DATE, TIME, DATETIME,
TIMESTAMP, YEAR, SET, and ENUM types.
See section 6.2 Column Types.
INSERT to insert a subset of a table's columns; those
columns that are not explicitly given values are set to their default
values.
SELECT and WHERE
parts of queries. For example:
mysql> SELECT CONCAT(first_name, " ", last_name)
-> FROM tbl_name
-> WHERE income/dependents > 10000 AND age > 30;
GROUP BY and ORDER BY clauses with
expressions. Support for group functions (COUNT(),
COUNT(DISTINCT ...), AVG(), STD(), SUM(),
MAX(), and MIN()).
LEFT OUTER JOIN and RIGHT OUTER JOIN with ANSI
SQL and ODBC syntax.
DELETE, INSERT, REPLACE, and UPDATE return
the number of rows that were changed (affected). It is possible to return
the number of rows matched instead by setting a flag when connecting to the
server.
MySQL-specific SHOW command can be used to retrieve
information about databases, tables, and indexes. The EXPLAIN command
can be used to determine how the optimiser resolves a query.
ABS is a valid column name. The only restriction is that for a
function call, no spaces are allowed between the function name and the
`(' that follows it. See section 6.1.7 Is MySQL Picky About Reserved Words?.
MySQL Server with some
databases that contain 50 million records and we know of users that
use MySQL Server with 60,000 tables and about 5,000,000,000 rows.
MySQL Server).
An index may use a prefix of a CHAR or VARCHAR field.
MySQL server using TCP/IP Sockets,
Unix Sockets (Unix), or Named Pipes (NT).
ODBC (Open-DataBase-Connectivity) support for Win32 (with source).
All ODBC 2.5 functions and many others. For example, you can use
MS Access to connect to your MySQL server. See section 8.3 MySQL ODBC Support.
MySQL
server is started. To see an example of very advanced sorting, look
at the Czech sorting code. MySQL Server supports many different
character sets that can be specified at compile and runtime.
myisamchk, a very fast utility for table checking,
optimisation, and repair. All of the functionality of myisamchk
is also available through the SQL interface as well.
See section 4 Database Administration.
MySQL programs can be invoked with the --help or -?
options to obtain online assistance.
This section addresses the questions ``How stable is MySQL Server?'' and ``Can I depend on MySQL Server in this project?'' We will try to clarify these issues and answer some important questions that concern many potential users. The information in this section is based on data gathered from the mailing list, which is very active in identifying problems as well as reporting types of use.
Original code stems back from the early '80s, providing a stable code
base, and the ISAM table format remains backward-compatible.
At TcX, the predecessor of MySQL AB, MySQL code has worked
in projects since mid-1996, without any problems.
When the MySQL Database Software was released to a wider public,
we noticed that there were
some pieces of ``untested code'' that were quickly found by the new
users who made different types of queries from us. Each new release
has had fewer portability problems (even though each new release has
had many new features).
Each release of the MySQL Server has been usable. There have only
been problems
when users try code from the ``gray zones.'' Naturally, new users
don't know what the gray zones are; this section attempts to indicate
those that are currently known.
The descriptions mostly deal with Version 3.23 and 4.0 of MySQL Server.
All known and reported bugs are fixed in the latest version, with the
exception of those listed in the bugs section, which are things that
are design-related. See section 1.8.5 Known Errors and Design Deficiencies in MySQL.
The MySQL Server design is multi-layered with independent modules.
Some of the newer modules are listed here with an indication of how
well-tested each of them is:
MySQL 4.x.
InnoDB tables -- Stable (in 3.23 from 3.23.49)
InnoDB transactional storage engine has been declared
stable in the MySQL 3.23 tree, starting from version 3.23.49.
InnoDB is being used in large, heavy-load production systems.
BDB tables -- Gamma
Berkeley DB code is very stable, but we are still improving
the BDB transactional storage engine interface in
MySQL Server, so it will take some time before this is as well
tested as the other table types.
FULLTEXT -- Beta
MySQL 4.0.
MyODBC 3.51 (uses ODBC SDK 3.51) -- Stable
MyISAM tables -- Gamma
MyISAM storage
engine that checks if the table was closed properly on open and
executes an automatic check/repair of the table if it wasn't.
MyISAM tables in MySQL 4.0 for faster
insert of many rows.
fcntl()). In these cases, you should
run mysqld with the --skip-external-locking flag.
Problems are known to occur on some Linux systems, and on SunOS when
using NFS-mounted filesystems.
MySQL AB provides high-quality support for paying customers,
but the MySQL mailing list usually provides answers to common
questions. Bugs are usually fixed right away with a patch; for serious
bugs, there is almost always a new release.
MySQL Version 3.22 had a 4G limit on table size. With the
MyISAM table type in MySQL Version 3.23, the maximum table
size was pushed up to 8 million terabytes (2 ^ 63 bytes).
Note, however, that operating systems have their own file-size limits. Here are some examples:
| Operating System | File-Size Limit |
| Linux-Intel 32 bit | 2G, 4G or more, depends on Linux version |
| Linux-Alpha | 8T (?) |
| Solaris 2.5.1 | 2G (possible 4G with patch) |
| Solaris 2.6 | 4G (can be changed with flag) |
| Solaris 2.7 Intel | 4G |
| Solaris 2.7 UltraSPARC | 512G |
On Linux 2.2 you can get bigger tables than 2G by using the LFS patch for the ext2 filesystem. On Linux 2.4 patches also exist for ReiserFS to get support for big files.
This means that the table size for MySQL databases is normally
limited by the operating system.
By default, MySQL tables have a maximum size of about 4G. You can
check the maximum table size for a table with the SHOW TABLE STATUS
command or with the myisamchk -dv table_name.
See section 4.5.6 SHOW Syntax.
If you need bigger tables than 4G (and your operating system supports
this), you should set the AVG_ROW_LENGTH and MAX_ROWS
parameter when you create your table. See section 6.5.3 CREATE TABLE Syntax. You can
also set these later with ALTER TABLE. See section 6.5.4 ALTER TABLE Syntax.
If your big table is going to be read-only, you could use
myisampack to merge and compress many tables to one.
myisampack usually compresses a table by at least 50%, so you can
have, in effect, much bigger tables. See section 4.7.4 myisampack, The MySQL Compressed Read-only Table Generator.
You can go around the operating system file limit for MyISAM data
files by using the RAID option. See section 6.5.3 CREATE TABLE Syntax.
Another solution can be the included MERGE library, which allows
you to handle a collection of identical tables as one.
See section 7.2 MERGE Tables.
The MySQL Server itself has no problems with Year 2000 (Y2K)
compliance:
MySQL Server uses Unix time functions and has no problems with dates
until 2069; all 2-digit years are regarded to be in the range
1970 to 2069, which means that if you store 01 in a
year column, MySQL Server treats it as 2001.
MySQL date functions are stored in one file, `sql/time.cc',
and are coded very carefully to be year 2000-safe.
MySQL Version 3.22 and later, the YEAR column type
can store years 0 and 1901 to 2155 in 1 byte and
display them using 2 or 4 digits.
You may run into problems with applications that use MySQL Server
in a way that is not Y2K-safe. For example, many old applications store
or manipulate years using 2-digit values (which are ambiguous) rather than
4-digit values. This problem may be compounded by applications that use
values such as 00 or 99 as ``missing'' value indicators.
Unfortunately, these problems may be difficult to fix because different applications may be written by different programmers, each of whom may use a different set of conventions and date-handling functions.
Here is a simple demonstration illustrating that MySQL Server
doesn't have any problems with dates until the year 2030:
mysql> DROP TABLE IF EXISTS y2k;
Query OK, 0 rows affected (0.01 sec)
mysql> CREATE TABLE y2k (date DATE,
-> date_time DATETIME,
-> time_stamp TIMESTAMP);
Query OK, 0 rows affected (0.00 sec)
mysql> INSERT INTO y2k VALUES
-> ("1998-12-31","1998-12-31 23:59:59",19981231235959),
-> ("1999-01-01","1999-01-01 00:00:00",19990101000000),
-> ("1999-09-09","1999-09-09 23:59:59",19990909235959),
-> ("2000-01-01","2000-01-01 00:00:00",20000101000000),
-> ("2000-02-28","2000-02-28 00:00:00",20000228000000),
-> ("2000-02-29","2000-02-29 00:00:00",20000229000000),
-> ("2000-03-01","2000-03-01 00:00:00",20000301000000),
-> ("2000-12-31","2000-12-31 23:59:59",20001231235959),
-> ("2001-01-01","2001-01-01 00:00:00",20010101000000),
-> ("2004-12-31","2004-12-31 23:59:59",20041231235959),
-> ("2005-01-01","2005-01-01 00:00:00",20050101000000),
-> ("2030-01-01","2030-01-01 00:00:00",20300101000000),
-> ("2050-01-01","2050-01-01 00:00:00",20500101000000);
Query OK, 13 rows affected (0.01 sec)
Records: 13 Duplicates: 0 Warnings: 0
mysql> SELECT * FROM y2k;
+------------+---------------------+----------------+
| date | date_time | time_stamp |
+------------+---------------------+----------------+
| 1998-12-31 | 1998-12-31 23:59:59 | 19981231235959 |
| 1999-01-01 | 1999-01-01 00:00:00 | 19990101000000 |
| 1999-09-09 | 1999-09-09 23:59:59 | 19990909235959 |
| 2000-01-01 | 2000-01-01 00:00:00 | 20000101000000 |
| 2000-02-28 | 2000-02-28 00:00:00 | 20000228000000 |
| 2000-02-29 | 2000-02-29 00:00:00 | 20000229000000 |
| 2000-03-01 | 2000-03-01 00:00:00 | 20000301000000 |
| 2000-12-31 | 2000-12-31 23:59:59 | 20001231235959 |
| 2001-01-01 | 2001-01-01 00:00:00 | 20010101000000 |
| 2004-12-31 | 2004-12-31 23:59:59 | 20041231235959 |
| 2005-01-01 | 2005-01-01 00:00:00 | 20050101000000 |
| 2030-01-01 | 2030-01-01 00:00:00 | 20300101000000 |
| 2050-01-01 | 2050-01-01 00:00:00 | 00000000000000 |
+------------+---------------------+----------------+
13 rows in set (0.00 sec)
This shows that the DATE and DATETIME types will not
give any problems with future dates (they handle dates until the year
9999).
The TIMESTAMP type, which is used to store the current time, has a
range up to only 2030-01-01. TIMESTAMP has a range of
1970 to 2030 on 32-bit machines (signed value). On 64-bit
machines it handles times up to 2106 (unsigned value).
Even though MySQL Server is Y2K-compliant, it is your responsibility
to provide unambiguous input. See section 6.2.2.1 Y2K Issues and Date Types for MySQL Server's
rules for dealing with ambiguous date input data (data containing 2-digit
year values).
MySQL AB is the company of the MySQL founders and main
developers. MySQL AB was originally established in Sweden by
David Axmark, Allan Larsson, and Michael Monty Widenius.
All the developers of the MySQL server are employed by the company.
We are a virtual organisation with people in a dozen countries around
the world. We communicate extensively over the Net every day with each
other and with our users, supporters and partners.
We are dedicated to developing the MySQL software and spreading
our database to new users. MySQL AB owns the copyright to the
MySQL source code, the MySQL logo and trademark, and this
manual. See section 1.2 What Is MySQL?.
The MySQL core values show our dedication to MySQL and
Open Source.
We want the MySQL Database Software to be:
MySQL AB and the people at MySQL AB:
Open Source philosophy and support the
Open Source community.
The MySQL web site (http://www.mysql.com/)
provides the latest information about MySQL and MySQL AB.
One of the most common questions we encounter is: ``How can you make a living from something you give away for free?'' This is how.
MySQL AB makes money on support, services, commercial licenses,
and royalties, and we use these revenues to fund product development
and to expand the MySQL business.
The company has been profitable since its inception. In October 2001, we accepted venture financing from leading Scandinavian investors and a handful of business angels. This investment is used to solidify our business model and build a basis for sustainable growth.
MySQL AB is run and owned by the founders and main developers of
the MySQL database. The developers are committed to giving support
to customers and other users in order to stay in touch with their needs
and problems. All our support is given by qualified developers. Really
tricky questions are answered by Michael Monty Widenius, principal
author of the MySQL Server.
See section 1.4.1 Support Offered by MySQL AB.
For more information and ordering support at various levels, see http://www.mysql.com/support/ or contact our sales staff at sales@mysql.com.
MySQL AB delivers MySQL and related training worldwide.
We offer both open courses and in-house courses tailored to the
specific needs of your company. MySQL Training is also available
through our partners, the Authorised MySQL Training Centers.
Our training material uses the same example databases as our
documentation and our sample applications, and it is always updated
to reflect the latest MySQL version. Our trainers are backed by
the development team to guarantee the quality of the training and the
continuous development of the course material. This also ensures
that no questions raised during the courses remain unanswered.
Attending our training courses will enable you to achieve your goals
related to your MySQL applications. You will also:
MySQL Certification.
If you are interested in our training as a potential participant or as a training partner, please visit the training section at http://www.mysql.com/training/ or contact us at: training@mysql.com.
For details about the MySQL Certification Program, please see
http://www.mysql.com/certification/.
MySQL AB and its Authorised Partners offer consulting
services to users of MySQL Server and to those who embed
MySQL Server in their own software, all over the world.
Our consultants can help you design and tune your databases, construct
efficient queries, tune your platform for optimal performance, resolve
migration issues, set up replication, build robust transactional
applications, and more.
We also help customers embed MySQL Server in their products and
applications for large-scale deployment.
Our consultants work in close collaboration with our development team,
which ensures the technical quality of our professional services.
Consulting assignments range from 2-day power-start sessions to
projects that span weeks and months. Our expertise not only covers
MySQL Server, but also extends into programming and scripting
languages such as PHP, Perl, and more.
If you are interested in our consulting services or want to become a consulting partner, please visit the consulting section of our web site at http://www.mysql.com/consulting/ or contact our consulting staff at consulting@mysql.com.
The MySQL database is released under the
GNU General Public License (GPL).
This means that the MySQL software can be used free of charge
under the GPL. If you do not want to be bound by the GPL
terms (like the requirement that your own application becomes GPL
as well), you may purchase a commercial license for the same product
from MySQL AB.
See http://www.mysql.com/products/pricing.html.
Since MySQL AB owns the copyright to the MySQL source code,
we are able to employ Dual Licensing which means that the same
product is available under GPL and under a commercial
license. This does not in any way affect the Open Source
commitment of MySQL AB. For details about when a commercial
license is required, please see section 1.4.3 MySQL Licenses.
We also sell commercial licenses of third-party Open Source GPL
software that adds value to MySQL Server. A good example is the
InnoDB transactional storage engine that offers ACID
support, row-level locking, crash recovery, multi-versioning, foreign
key support, and more. See section 7.5 InnoDB Tables.
MySQL AB has a worldwide partner programme that covers training
courses, consulting & support, publications plus reselling and
distributing MySQL and related products. MySQL AB Partners
get visibility on the http://www.mysql.com/ web site and the right
to use special versions of the MySQL trademarks to identify their
products and promote their business.
If you are interested in becoming a MySQL AB Partner, please e-mail
partner@mysql.com.
The word MySQL and the MySQL dolphin logo are trademarks of
MySQL AB. See section 1.4.4 MySQL AB Logos and Trademarks.
These trademarks represent a significant value that the MySQL
founders have built over the years.
The MySQL web site (http://www.mysql.com/) is popular among
developers and users. In October 2001, we served 10 million page views.
Our visitors represent a group that makes purchase decisions and
recommendations for both software and hardware. Twelve percent of our
visitors authorise purchase decisions, and only nine percent are not
involved in purchase decisions at all. More than 65% have made one or
more online business purchase within the last half-year, and 70% plan
to make one in the next months.
The MySQL web site (http://www.mysql.com/)
provides the latest information about MySQL and MySQL AB.
For press service and inquiries not covered in our News releases (http://www.mysql.com/news/), please send e-mail to press@mysql.com.
If you have a valid support contract with MySQL AB, you will
get timely, precise answers to your technical questions about the
MySQL software. For more information, see section 1.4.1 Support Offered by MySQL AB.
On our website, see http://www.mysql.com/support/, or send
an e-mail message to sales@mysql.com.
For information about MySQL training, please visit the training
section at http://www.mysql.com/training/. If you have
restricted access to the Internet, please contact the MySQL AB
training staff at training@mysql.com.
See section 1.3.1.2 Training and Certification.
For information on the MySQL Certification Program, please see
http://www.mysql.com/certification/.
See section 1.3.1.2 Training and Certification.
If you're interested in consulting, please visit the consulting
section at http://www.mysql.com/consulting/. If you have
restricted access to the Internet, please contact the MySQL AB
consulting staff at consulting@mysql.com.
See section 1.3.1.3 Consulting.
Commercial licenses may be purchased online at
https://order.mysql.com/. There you will also find information
on how to fax your purchase order to MySQL AB. More information
about licensing can be found at
http://www.mysql.com/products/pricing.html.
If you have
questions regarding licensing or you want a quote for a high-volume
license deal, please fill in the contact form on our web site
(http://www.mysql.com/) or send an e-mail message
to licensing@mysql.com (for licensing questions) or to
sales@mysql.com (for sales inquiries).
See section 1.4.3 MySQL Licenses.
If you represent a business that is interested in partnering with
MySQL AB, please send e-mail to partner@mysql.com.
See section 1.3.1.5 Partnering.
For more information on the MySQL trademark policy, refer to
http://www.mysql.com/company/trademark.html or send e-mail to
trademark@mysql.com.
See section 1.4.4 MySQL AB Logos and Trademarks.
If you are interested in any of the MySQL AB jobs listed in our
jobs section (http://www.mysql.com/company/jobs/),
please send an e-mail message to jobs@mysql.com.
Please do not send your CV as an attachment, but rather as plain text
at the end of your e-mail message.
For general discussion among our many users, please direct your attention to the appropriate mailing list. See section 1.7.1 MySQL Mailing Lists.
Reports of errors (often called bugs), as well as questions and
comments, should be sent to the mailing list at
mysql@lists.mysql.com. If you have found a sensitive
security bug in the MySQL Server, please send an e-mail
to security@mysql.com.
See section 1.7.1.3 How to Report Bugs or Problems.
If you have benchmark results that we can publish, please contact us at benchmarks@mysql.com.
If you have any suggestions concerning additions or corrections to this manual, please send them to the manual team at docs@mysql.com.
For questions or comments about the workings or content of the
MySQL web site (http://www.mysql.com/),
please send e-mail to webmaster@mysql.com.
MySQL AB has a privacy policy, which can be read at
http://www.mysql.com/company/privacy.html.
For any queries regarding this policy, please e-mail
privacy@mysql.com.
For all other inquires, please send e-mail to info@mysql.com.
This section describes MySQL support and licensing arrangements.
Technical support from MySQL AB means individualised answers
to your unique problems direct from the software engineers who code
the MySQL database engine.
We try to take a broad and inclusive view of technical support. Almost
any problem involving MySQL software is important to us if it's
important to you.
Typically customers seek help on how to get different commands and
utilities to work, remove performance bottlenecks, restore crashed
systems, understand operating system or networking impacts on MySQL,
set up best practices for backup and recovery, utilise APIs, etc.
Our support covers only the MySQL server and our own utilities,
not third-party products that access the MySQL server, though we
try to help with these where we can.
Detailed information about our various support options is given at http://www.mysql.com/support/, where support contracts can also be ordered online. If you have restricted access to the Internet, contact our sales staff at sales@mysql.com.
Technical support is like life insurance. You can live happily
without it for years, but when your hour arrives it becomes
critically important, yet it's too late to buy it!
If you use MySQL Server for important applications and encounter
sudden troubles, it might take too long to figure out all the answers
yourself. You may need immediate access to the most experienced
MySQL troubleshooters available, those employed by MySQL AB.
MySQL AB owns the copyright to the MySQL source code,
the MySQL logos and trademarks and this manual.
See section 1.3 What Is MySQL AB?.
Several different licenses are relevant to the MySQL
distribution:
MySQL-specific source in the server, the mysqlclient
library and the client, as well as the GNU readline library
is covered by the GNU General Public License.
See section H GNU General Public License.
The text of this license can also be found as the file `COPYING'
in the distributions.
GNU getopt library is covered by the
GNU Lesser General Public License.
See section I GNU Lesser General Public License.
regexp library) are covered
by a Berkeley-style copyright.
MySQL (3.22 and earlier) are subject to a
more strict license
(http://www.mysql.com/products/mypl.html).
See the documentation of the specific version for information.
GPL-style license.
Use of the manual is subject to the following terms:
MySQL AB is required.
For information about how the MySQL licenses work in practice,
please refer to section 1.4.3 MySQL Licenses.
Also see section 1.4.4 MySQL AB Logos and Trademarks.
The MySQL software is released under the
GNU General Public License (GPL),
which probably is the best known Open Source license.
The formal terms of the GPL license can be found at
http://www.gnu.org/licenses/.
See also http://www.gnu.org/licenses/gpl-faq.html and
http://www.gnu.org/philosophy/enforcing-gpl.html.
Since the MySQL software is released under the GPL,
it may often be used for free, but for certain uses you may want
or need to buy commercial licenses from MySQL AB at
https://order.mysql.com/.
See http://www.mysql.com/products/licensing.html for
more information.
Older versions of MySQL (3.22 and earlier) are subject to a
more strict license
(http://www.mysql.com/products/mypl.html).
See the documentation of the specific version for information.
Please note that the use of the MySQL software under commercial
license, GPL, or the old MySQL license does not
automatically give you the right to use MySQL AB trademarks.
See section 1.4.4 MySQL AB Logos and Trademarks.
The GPL license is contagious in the sense that when a program
is linked to a GPL program all the source code for all the parts
of the resulting product must also be released under the GPL.
Otherwise you break the license terms and forfeit your right to use the
GPL program altogether and also risk damages.
You need a commercial license:
GPL code from the MySQL
software and don't want the resulting product to be GPL, maybe
because you want to build a commercial product or keep the added
non-GPL code closed source for other reasons. When purchasing
commercial licenses, you are not using the MySQL software under
GPL even though it's the same code.
GPL application that only works with the
MySQL software and ship it with the MySQL software. This type
of solution is actually considered to be linking even if it's done over
a network.
MySQL software without providing
the source code as required under the GPL license.
MySQL
database even if you don't formally need a commercial license.
Purchasing support directly from MySQL AB is another good way
of contributing to the development of the MySQL software, with
immediate advantages for you.
See section 1.4.1 Support Offered by MySQL AB.
If you require a license, you will need one for each installation of the
MySQL software. This covers any number of CPUs on a machine, and there
is no artificial limit on the number of clients that connect to the server
in any way.
For commercial licenses, please visit our website at http://www.mysql.com/products/licensing.html. For support contracts, see http://www.mysql.com/support/. If you have special needs or you have restricted access to the Internet, please contact our sales staff at sales@mysql.com.
You can use the MySQL software for free under the GPL if
you adhere to the conditions of the GPL.
For more complete coverage of the common questions about the GPL
see the generic FAQ from the Free Software Foundation at
http://www.gnu.org/licenses/gpl-faq.html.
Some common cases:
MySQL
source code under the GPL with your product.
MySQL source code bundled with other
programs that are not linked to or dependent on the MySQL system
for their functionality even if you sell the distribution commercially.
This is called mere aggregation in the GPL license.
MySQL
system, you can use it for free.
MySQL servers for your customers.
However, we do encourage people to use ISPs that have MySQL support,
as this will give them the confidence that if they have some problem
with the MySQL installation, their ISP will in fact have the
resources to solve the problem for them.
Note that even if an ISP does not have a commercial license for
MySQL Server, they should at least give their customers read
access to the source of the MySQL installation so that the
customers can verify that it is patched correctly.
MySQL Database Software in conjunction with a
web server, you do not need a commercial license (so long as it is not
a product you distribute). This is true even if you run a commercial
web server that uses MySQL Server, because you are not
distributing any part of the MySQL system. However, in this
case we would like you to purchase MySQL support because the
MySQL software is helping your enterprise.
If your use of MySQL database software does not require a commercial
license, we encourage you to purchase support from MySQL AB anyway.
This way you contribute toward MySQL development and also gain
immediate advantages for yourself. See section 1.4.1 Support Offered by MySQL AB.
If you use the MySQL database software in a commercial context
such that you profit by its use, we ask that you further the development
of the MySQL software by purchasing some level of support. We feel
that if the MySQL database helps your business, it is reasonable to
ask that you help MySQL AB.
(Otherwise, if you ask us support questions, you are not only using
for free something into which we've put a lot a work, you're asking
us to provide free support, too.)
Many users of the MySQL database want to display the
MySQL AB dolphin logo on their web sites, books, or
boxed products. We welcome and encourage this, although it should be
noted that the word MySQL and the MySQL dolphin logo
are trademarks of MySQL AB and may only be used as stated in
our trademark policy at
http://www.mysql.com/company/trademark.html.
The MySQL dolphin logo was designed by the Finnish advertising
agency Priority in 2001. The dolphin was chosen as a suitable symbol
for the MySQL database since it is a smart, fast, and lean animal,
effortlessly navigating oceans of data. We also happen to like dolphins.
The original MySQL logo may only be used by representatives of
MySQL AB and by those having a written agreement allowing them
to do so.
We have designed a set of special Conditional Use logos that may be
downloaded from our web site at
http://www.mysql.com/press/logos.html
and used on third-party web sites without written permission from
MySQL AB.
The use of these logos is not entirely unrestricted but, as the name
implies, subject to our trademark policy that is also available on our
web site. You should read through the trademark policy if you plan to
use them. The requirements are basically:
MySQL AB, are the creator and
owner of the site that displays the MySQL trademark.
MySQL AB
or to the value of MySQL AB trademarks. We reserve the right to
revoke the right to use the MySQL AB trademark.
MySQL database under GPL in an
application, your application must be Open Source and
be able to connect to a MySQL server.
Contact us at trademark@mysql.com to inquire about special arrangements to fit your needs.
In the following cases you need a written permission from MySQL AB
before using MySQL logos:
MySQL AB logo anywhere except on your web site.
MySQL AB logo except the Conditional Use
logos mentioned previously on web sites or elsewhere.
Out of legal and commercial reasons we have to monitor the use of MySQL
trademarks on products, books, etc. We will usually require a fee for
displaying MySQL AB logos on commercial products, since we think
it is reasonable that some of the revenue is returned to fund further
development of the MySQL database.
MySQL partnership logos may only be used by companies and persons
having a written partnership agreement with MySQL AB. Partnerships
include certification as a MySQL trainer or consultant.
Please see section 1.3.1.5 Partnering.
MySQL in Printed Text or Presentations
MySQL AB welcomes references to the MySQL database, but
note that the word MySQL is a trademark of MySQL AB.
Because of this, you should append the trademark symbol (TM) to
the first or most prominent use of the word MySQL in a text and
where appropriate, state that MySQL is a trademark of
MySQL AB. Please refer to our trademark policy at
http://www.mysql.com/company/trademark.html for details.
MySQL in Company and Product Names
Use of the word MySQL in product or company names or in Internet
domain names is not allowed without written permission from MySQL AB.
Long promised by MySQL AB and long awaited by our users,
MySQL Server 4.0 is now available in production version.
MySQL 4.0 is available for download from http://www.mysql.com/ and our mirrors. MySQL 4.0 has been tested by a large number of users and is in production use at many big sites.
Main new features of MySQL Server 4.0 are geared toward our existing business and community users, enhancing the MySQL database software as the solution for mission-critical, heavy-load database systems. Other new features target the users of embedded databases.
MySQL Version 4.0.12 has been declared stable for production use in March 2003. This means that only bugfixes are done for the 4.0 release series, and only critical bugfixes for the older 3.23 series. See section 2.5.3 Upgrading From Version 3.23 to 4.0.
New features are being added in MySQL 4.1, which is already available from our BitKeeper source tree. See section 1.6 MySQL 4.1 In A Nutshell.
INSERTs, searching on
packed indexes, creation of FULLTEXT indexes, as well as
COUNT(DISTINCT).
InnoDB storage engine is now offered as a feature of the
standard MySQL server, including full support for ACID transactions,
foreign keys with cascading update/delete,
and row-level locking.
See section 7.5 InnoDB Tables.
FULLTEXT search properties of MySQL Server 4.0 enable
the use of FULLTEXT indexing of large text masses with both binary
and natural-language searching logic. Users can customise minimal word
length and define their own stop word lists in any human language,
enabling a new set of applications to be built on MySQL Server.
See section 6.8 MySQL Full-text Search.
TRUNCATE TABLE (like in Oracle) and IDENTITY
as a synonym for automatically incremented keys (like in Sybase).
UNION statement, a long-awaited standard SQL feature.
latin1_de, which corrects the German sorting order,
placing German umlauts in the same order as German telephone books.
mysqld parameters (startup options) can be set without taking
down the servers. See section 5.5.6 SET Syntax.
DELETE and UPDATE statements.
symbolic linking to MyISAM on the table
level (and not just the database level as before), as well as by enabling
symlink handling by default on Windows, we hope to show that we take
enhancement requests seriously.
SQL_CALC_FOUND_ROWS and FOUND_ROWS() make it
possible to know how many rows a query would have returned without a
LIMIT clause.
The news section in the manual includes a more in-depth list of features. See section D.3 Changes in release 4.0.x (Production).
libmysqld makes MySQL Server suitable for a vastly expanded realm of
applications. Using the embedded MySQL server library, one can
embed MySQL Server into various applications and electronics devices, where
the end user has no knowledge of there actually being an underlying
database. Embedded MySQL Server is ideal for use behind
the scenes in Internet appliances, public kiosks, turnkey
hardware/software combination units, high performance Internet
servers, self-contained databases distributed on CD-ROM, etc.
Many users of libmysqld will benefit from the MySQL
Dual Licensing. For those not wishing to be bound by the GPL,
the software is also made available under a commercial license.
The embedded MySQL library uses the same interface as the normal
client library, so it is convenient and easy to use. See section 8.4.9 libmysqld, the Embedded MySQL Server Library.
MySQL Server 4.0 laid the foundation for new features such as nested subqueries and Unicode that have now already been implemented in version 4.1, and current work on SQL-99 stored procedures work being done for version 5.0, which form the top of the wish list for many of our customers.
With these additions, critics of the MySQL Database Server have to be more imaginative than ever in pointing out deficiencies in the MySQL Database Management System. For long already known for its stability, speed, and ease of use, MySQL Server will then match the requirement checklist of very demanding buyers.
The features below are already implemented in MySQL 4.1. Very few other features are still planned for MySQL 4.1. See section 1.9.1 New Features Planned For 4.1.
Most new features being coded right now, such as Stored Procedures, will be available in MySQL 5.0. See section 1.9.2 New Features Planned For 5.0.
SELECT * FROM t1 WHERE t1.a=(SELECT t2.b FROM t2); SELECT * FROM t1 WHERE (1,2,3) IN (SELECT a,b,c FROM t2);
FROM
part of a SELECT statement:
SELECT t1.a FROM t1, (SELECT * FROM t2) t3 WHERE t1.a=t3.a;
BTREE indexing is now supported for HEAP tables,
significantly improving response time for non-exact searches.
CREATE TABLE table LIKE table allows you to create a new table
with the exact structure of an existing table, using one single command.
SHOW WARNINGS shows warnings for the last command.
See section 4.5.6.9 SHOW WARNINGS | ERRORS.
HELP command that can be used in the mysql command line
client (and other clients) to get help for SQL commands.
Having this information on the server side has the advantage that any
information will always be applicable for that particular server version.
INSERT ... ON DUPLICATE KEY UPDATE ...
syntax. This allows you to UPDATE an existing row if the
INSERT would have caused a duplicate in a PRIMARY or
UNIQUE key (index).
See section 6.4.3 INSERT Syntax.
The news section in the manual includes a more in-depth list of features. See section D.2 Changes in release 4.1.x (Alpha).
New features are being added in MySQL 4.1, which is already available from our BitKeeper source tree. See section 2.3.4 Installing from the Development Source Tree.
The set of features that are being added to version 4.1 is mostly fixed. Additional development is already ongoing for version 5.0. The MySQL 4.1 will go through the steps of Alpha (during which time new features might still be added/changed), Beta (when we have feature freeze and only bug corrections are done) and Gamma (indicating that a production release is just weeks ahead) before 4.1 becomes be the new production release.
All binary releases pass our extensive test suite without any errors on any of the platforms we test on.
MySQL 4.1 is now in a pre-alpha stage, where our existing MySQL 4.1 users are compiling the source code themselves. See section 2.3.4 Installing from the Development Source Tree.
New development for MySQL is focused on the 5.0 release, featuring Stored Procedures and other new features. See section 1.9.2 New Features Planned For 5.0.
This section introduces you to the MySQL mailing lists, and gives some guidelines as to how to use them. By subscribing to a mailing list, you will receive as e-mail messages all other postings on the list, and you will be able to send in your own questions and answers.
To subscribe to the main MySQL mailing list, send a message to the electronic mail address mysql-subscribe@lists.mysql.com.
To unsubscribe from the main MySQL mailing list, send a message to the electronic mail address mysql-unsubscribe@lists.mysql.com.
Only the address to which you send your messages is significant. The subject line and the body of the message are ignored.
If your reply address is not valid, you can specify your address
explicitly, by adding a hyphen to the subscribe or unsubscribe command
word, followed by your address with the `@' character in your
address replaced by a `='. For example, to subscribe
your_name@host.domain, send a message to
mysql-subscribe-your_name=host.domain@lists.mysql.com.
Mail to mysql-subscribe@lists.mysql.com or mysql-unsubscribe@lists.mysql.com is handled automatically by the ezmlm mailing list processor. Information about ezmlm is available at the ezmlm web site (http://www.ezmlm.org/).
To post a message to the list itself, send your message to
mysql@lists.mysql.com. However, please do not send mail about
subscribing or unsubscribing to mysql@lists.mysql.com because any
mail sent to that address is distributed automatically to thousands of other
users.
Your local site may have many subscribers to mysql@lists.mysql.com.
If so, it may have a local mailing list, so messages sent from
lists.mysql.com to your site are propagated to the local list. In such
cases, please contact your system administrator to be added to or dropped
from the local MySQL list.
If you wish to have traffic for a mailing list go to a separate mailbox in
your mail program, set up a filter based on the message headers. You can
use either the List-ID: or Delivered-To: headers to identify
list messages.
The following MySQL mailing lists exist:
announce-subscribe@lists.mysql.com announce
mysql-subscribe@lists.mysql.com mysql
mysql-digest-subscribe@lists.mysql.com mysql-digest
mysql list in digest form. That means you get all individual
messages, sent as one large mail message once a day.
bugs-subscribe@lists.mysql.com bugs
bugs-digest-subscribe@lists.mysql.com bugs-digest
bugs list in digest form.
internals-subscribe@lists.mysql.com internals
internals-digest-subscribe@lists.mysql.com internals-digest
internals list.
mysqldoc-subscribe@lists.mysql.com mysqldoc
mysqldoc-digest-subscribe@lists.mysql.com mysqldoc-digest
mysqldoc list.
java-subscribe@lists.mysql.com java
java-digest-subscribe@lists.mysql.com java-digest
java list.
win32-subscribe@lists.mysql.com win32
win32-digest-subscribe@lists.mysql.com win32-digest
win32 list.
myodbc-subscribe@lists.mysql.com myodbc
myodbc-digest-subscribe@lists.mysql.com myodbc-digest
myodbc list.
mysqlcc-subscribe@lists.mysql.com mysqlcc
MySQL Control Center graphical client.
mysqlcc-digest-subscribe@lists.mysql.com mysqlcc-digest
mysqlcc list.
plusplus-subscribe@lists.mysql.com plusplus
plusplus-digest-subscribe@lists.mysql.com plusplus-digest
plusplus list.
msql-mysql-modules-subscribe@lists.mysql.com msql-mysql-modules
msql-mysql-modules-digest-subscribe@lists.mysql.com msql-mysql-modules-digest
msql-mysql-modules list.
You subscribe or unsubscribe to all lists in the same way as described
previously. In your subscribe or unsubscribe message, just put the appropriate
mailing list name rather than mysql. For example, to subscribe to or
unsubscribe from the myodbc list, send a message to
myodbc-subscribe@lists.mysql.com or
myodbc-unsubscribe@lists.mysql.com.
If you can't get an answer for your questions from the mailing list, one option is to pay for support from MySQL AB, which will put you in direct contact with MySQL developers. See section 1.4.1 Support Offered by MySQL AB.
The following table shows some MySQL mailing in languages other than English. Note that these are not operated by MySQL AB, so we can't guarantee the quality on these.
mysql-france-subscribe@yahoogroups.com A French mailing list
list@tinc.net A Korean mailing list
subscribe mysql your@e-mail.address to this list.
mysql-de-request@lists.4t2.com A German mailing list
subscribe mysql-de your@e-mail.address to this list.
You can find information about this mailing list at
http://www.4t2.com/mysql/.
mysql-br-request@listas.linkway.com.br A Portugese mailing list
subscribe mysql-br your@e-mail.address to this list.
mysql-alta@elistas.net A Spanish mailing list
subscribe mysql your@e-mail.address to this list.
Before posting a bug report or question, please do the following:
If you can't find an answer in the manual or the archives, 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@lists.mysql.com.
Our bugs database is public, and can be browsed and searched by anyone at http://bugs.mysql.com/. If you log into the system, you will also be able to enter new reports.
Writing a good bug report takes patience, but doing it right the first time saves time both for us and for yourself. A good bug report containing a full test case for the bug will make it very likely that we will fix it in the next release. This section will help you write your report correctly so that you don't waste your time doing things that may not help us much or at all.
We encourage everyone to use the mysqlbug script to generate a bug
report (or a report about any problem), if possible. mysqlbug can be
found in the `scripts' directory in the source distribution, or for a
binary distribution, in the `bin' directory under your MySQL
installation directory. If you are unable to use mysqlbug (for
instance, if you are running on Windows), you should still include all
the necessary information listed in this section (most importantly a
description of the operating system, and the MySQL version).
The mysqlbug script helps you generate a report by determining much
of the following information automatically, but if something important is
missing, please include it with your message! Please read this section
carefully and make sure that all the information described here is included
in your report.
Preferably, you should test the problem using the latest production or
development version of MySQL Server before posting! Anyone should be
able to repeat the bug by just using 'mysql test < script' on the
included testcase or run the shell or Perl script that is included in the
bug report.
All bugs posted in the bugs database or on the bugs@lists.mysql.com list will be corrected or documented in the next MySQL release! If only small code changes are needed to correct this problem, we will also post a patch that fixes the problem.
The normal place to report bugs is http://bugs.mysql.com/.
If you have found a sensitive security bug in MySQL, you should send an e-mail to security@mysql.com.
If you have a repeatable bug report you can report this into the bugs
database at http://bugs.mysql.com/. Note that even in this case
it's good to run the mysqlbug script first to find information
about your system. Any bug that we are able to repeat has a high chance
of being fixed in the next MySQL release.
For other problem reports, you can use mysql@lists.mysql.com.
Remember that it is possible to respond to a message containing too much information, but not to one containing too little. Often people omit facts because they think they know the cause of a problem and assume that some details don't matter. A good principle is: if you are in doubt about stating something, state it! It is a thousand times faster and less troublesome to write a couple of lines more in your report than to be forced to ask again and wait for the answer because you didn't include enough information the first time.
The most common errors are that people don't indicate the version number of the MySQL distribution they are using, or don't indicate what platform they have the MySQL server installed on (including the platform version number). This is highly relevant information, and in 99 cases out of 100 the bug report is useless without it! Very often we get questions like, ``Why doesn't this work for me?'' Then we find that the feature requested wasn't implemented in that MySQL version, or that a bug described in a report has been fixed already in newer MySQL versions. Sometimes the error is platform-dependent; in such cases, it is next to impossible to fix anything without knowing the operating system and the version number of the platform.
Remember also to provide information about your compiler, if it is related to the problem. Often people find bugs in compilers and think the problem is MySQL-related. Most compilers are under development all the time and become better version by version. To determine whether your problem depends on your compiler, we need to know what compiler is used. Note that every compiling problem should be regarded as a bug report and reported accordingly.
It is most helpful when a good description of the problem is included in the bug report. That is, a good example of all the things you did that led to the problem and the problem itself exactly described. The best reports are those that include a full example showing how to reproduce the bug or problem. See section E.1.6 Making a Test Case If You Experience Table Corruption.
If a program produces an error message, it is very important to include the message in your report! If we try to search for something from the archives using programs, it is better that the error message reported exactly matches the one that the program produces. (Even the case should be observed!) You should never try to remember what the error message was; instead, copy and paste the entire message into your report!
If you have a problem with MyODBC, you should try to generate a MyODBC trace file. See section 8.3.7 Reporting Problems with MyODBC.
Please remember that many of the people who will read your report will
do so using an 80-column display. When generating reports or examples
using the mysql command-line tool, you should therefore use
the --vertical option (or the \G statement terminator)
for output that would exceed the available width for such a display
(for example, with the EXPLAIN SELECT statement; see the
example later in this section).
Please include the following information in your report:
mysqladmin version. mysqladmin can be
found in the `bin' directory under your MySQL installation
directory.
uname -a.
mysqld died, you should also report the query that crashed
mysqld. You can usually find this out by running mysqld with
logging enabled. See section E.1.5 Using Log Files to Find Cause of Errors in mysqld.
mysqldump --no-data db_name tbl_name1 tbl_name2 .... This is very easy
to do and is a powerful way to get information about any table in a database
that will help us create a situation matching the one you have.
SELECT statements, you
should always include the output of EXPLAIN SELECT ..., and at
least the number of rows that the SELECT statement produces. You
should also include the output from SHOW CREATE TABLE table_name
for each involved table. The more information you give about your
situation, the more likely it is that someone can help you! For
example, the following is an example of a very good bug report (it
should of course be posted with the mysqlbug script):
Example run using the mysql command-line tool (note the use of the
\G statement terminator for statements whose output width would
otherwise exceed that of an 80-column display device):
mysql> SHOW VARIABLES;
mysql> SHOW COLUMNS FROM ...\G
<output from SHOW COLUMNS>
mysql> EXPLAIN SELECT ...\G
<output from EXPLAIN>
mysql> FLUSH STATUS;
mysql> SELECT ...;
<A short version of the output from SELECT,
including the time taken to run the query>
mysql> SHOW STATUS;
<output from SHOW STATUS>
mysqld, try to provide an
input script that will reproduce the anomaly. This script should include any
necessary source files. The more closely the script can reproduce your
situation, the better. If you can make a reproduceable test case, you should
post it on http://bugs.mysql.com/ for high-priority treatment!
If you can't provide a script, you should at least include the output
from mysqladmin variables extended-status processlist in your mail to
provide some information of how your system is performing!
mysqldump and create a `README' file
that describes your problem.
Create a compressed archive of your files using
tar and gzip or zip, and use ftp to transfer the
archive to ftp://support.mysql.com/pub/mysql/secret/. Then enter
the problem into our bugs database at http://bugs.mysql.com/.
ftp to transfer it to
ftp://support.mysql.com/pub/mysql/secret/. If the data is really top
secret and you don't want to show it even to us, then go ahead and provide
an example using other names, but please regard this as the last choice.
mysqld
daemon and that you use to run any MySQL client programs. The
options to programs like mysqld and mysql, and to the
configure script, are often keys to answers and are very relevant!
It is never a bad idea to include them anyway! If you use any modules, such
as Perl or PHP, please include the version number(s) of those as well.
mysqlaccess, the output of mysqladmin reload, and all
the error messages you get when trying to connect! When you test your
privileges, you should first run mysqlaccess. After this, execute
mysqladmin reload version and try to connect with the program that
gives you trouble. mysqlaccess can be found in the `bin'
directory under your MySQL installation directory.
parse error, please check your syntax closely! If
you can't find something wrong with it, it's extremely likely that your
current version of MySQL Server doesn't support the query you are
using. If you are using the current version and the manual at
http://www.mysql.com/doc/ doesn't cover the
syntax you are using, MySQL Server doesn't support your query. In this
case, your only options are to implement the syntax yourself or e-mail
licensing@mysql.com and ask for an offer to implement it!
If the manual covers the syntax you are using, but you have an older version
of MySQL Server, you should check the MySQL change history to see
when the syntax was implemented. In this case, you have the option of
upgrading to a newer version of MySQL Server. See section D MySQL Change History.
myisamchk or CHECK TABLE and
REPAIR TABLE. See section 4 Database Administration.
mysqld should never crash a table if nothing killed it in the
middle of an update! If you can find the cause of mysqld dying,
it's much easier for us to provide you with a fix for the problem.
See section A.1 How to Determine What Is Causing Problems.
If you are a support customer, please cross-post the bug report to mysql-support@mysql.com for higher-priority treatment, as well as to the appropriate mailing list to see if someone else has experienced (and perhaps solved) the problem.
For information on reporting bugs in MyODBC, see section 8.3.4 How to Report Problems with MyODBC.
For solutions to some common problems, see section A Problems and Common Errors.
When answers are sent to you individually and not to the mailing list, it is considered good etiquette to summarise the answers and send the summary to the mailing list so that others may have the benefit of responses you received that helped you solve your problem!
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. Try to make your answer general enough that people other than the original poster may benefit from it. When you post to the list, 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; don't feel obliged to quote the entire original message.
Please don't post mail messages from your browser with HTML mode turned on! Many users don't read mail with a browser!
In addition to the various MySQL mailing lists, you can find experienced
community people on IRC (Internet Relay Chat).
These are the best networks/channels currently known to us:
#mysql
Primarily MySQL questions but other database and SQL questions welcome.
#mysqlphp
Questions about MySQL+PHP, a popular combo.
#mysqlperl
Questions about MySQL+Perl, another fairly popular combination.
#mysql
MySQL questions.
If you are looking for IRC client software to connect to an IRC network,
take a peek at X-Chat (http://www.xchat.org/).
X-Chat is available for Unix as well as for Windows platforms.
This section describes how MySQL relates to the ANSI SQL standards. MySQL Server has many extensions to the ANSI SQL standards, and here you will find out what they are and how to use them. You will also find information about functionality missing from MySQL Server, and how to work around some differences.
Our goal is to not, without a very good reason, restrict MySQL Server usability for any usage. Even if we don't have the resources to do development for every possible use, we are always willing to help and offer suggestions to people who are trying to use MySQL Server in new territories.
One of our main goals with the product is to continue to work toward
ANSI 99 compliancy, but without sacrificing speed or reliability.
We are not afraid to add extensions to SQL or support for non-SQL
features if this greatly increases the usability of MySQL Server for a big
part of our users. (The new HANDLER interface in MySQL Server 4.0
is an example of this strategy. See section 6.4.2 HANDLER Syntax.)
We will continue to support transactional and non-transactional databases to satisfy both heavy web/logging usage and mission-critical 24/7 usage.
MySQL Server was designed from the start to work with medium size databases (10-100 million rows, or about 100 MB per table) on small computer systems. We will continue to extend MySQL Server to work even better with terabyte-size databases, as well as to make it possible to compile a reduced MySQL version that is more suitable for hand-held devices and embedded usage. The compact design of the MySQL server makes both of these directions possible without any conflicts in the source tree.
We are currently not targeting realtime support or clustered databases (even if you can already do a lot of things with our replication services).
We don't believe that one should have native XML support in the database, but will instead add the XML support our users request from us on the client side. We think it's better to keep the main server code as ``lean and clean'' as possible and instead develop libraries to deal with the complexity on the client side. This is part of the strategy mentioned previously of not sacrificing speed or reliability in the server.
Entry-level SQL92. ODBC levels 0-3.51.
We are aiming toward supporting the full ANSI SQL99 standard, but without concessions to speed and quality of the code.
If you start mysqld with the --ansi option, the following
behaviour of MySQL Server changes:
|| is string concatenation instead of OR.
REAL will be a synonym for FLOAT instead of a synonym for
DOUBLE.
SERIALIZABLE.
See section 6.7.3 SET TRANSACTION Syntax.
GROUP BY that is not in the
field list.
This is the same as using
--sql-mode=REAL_AS_FLOAT,PIPES_AS_CONCAT,ANSI_QUOTES,
IGNORE_SPACE,SERIALIZE,ONLY_FULL_GROUP_BY.
MySQL Server includes some extensions 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. In some cases, you can write code that
includes MySQL extensions, but is still portable, by using comments
of the form /*! ... */. In this case, MySQL Server will parse and
execute the code within the comment as it would any other MySQL
statement, but other SQL servers will ignore the extensions. For example:
SELECT /*! STRAIGHT_JOIN */ col_name FROM table1,table2 WHERE ...
If you add a version number after the '!', the syntax will be
executed only if the MySQL version is equal to or newer than the used
version number:
CREATE /*!32302 TEMPORARY */ TABLE t (a int);
This means that if you have Version 3.23.02 or newer, MySQL
Server will use the TEMPORARY keyword.
The following is a list of MySQL extensions:
MEDIUMINT, SET, ENUM, and the
different BLOB and TEXT types.
AUTO_INCREMENT, BINARY, NULL,
UNSIGNED, and ZEROFILL.
BINARY attribute or use the BINARY cast, which causes
comparisons to be done according to the ASCII order used on the
MySQL server host.
db_name.tbl_name syntax. Some SQL servers provide
the same functionality but call this User space.
MySQL Server doesn't support tablespaces as in:
create table ralph.my_table...IN my_tablespace.
LIKE is allowed on numeric columns.
INTO OUTFILE and STRAIGHT_JOIN in a SELECT
statement. See section 6.4.1 SELECT Syntax.
SQL_SMALL_RESULT option in a SELECT statement.
EXPLAIN SELECT to get a description on how tables are joined.
INDEX or KEY in a CREATE TABLE
statement. See section 6.5.3 CREATE TABLE Syntax.
TEMPORARY or IF NOT EXISTS with CREATE TABLE.
COUNT(DISTINCT list) where list is more than one element.
CHANGE col_name, DROP col_name, or DROP
INDEX, IGNORE or RENAME in an ALTER TABLE
statement. See section 6.5.4 ALTER TABLE Syntax.
RENAME TABLE. See section 6.5.5 RENAME TABLE Syntax.
ADD, ALTER, DROP, or CHANGE
clauses in an ALTER TABLE statement.
DROP TABLE with the keywords IF EXISTS.
DROP TABLE statement.
LIMIT clause of the DELETE statement.
DELAYED clause of the INSERT and REPLACE
statements.
LOW_PRIORITY clause of the INSERT, REPLACE,
DELETE, and UPDATE statements.
LOAD DATA INFILE. In many cases, this syntax is compatible with
Oracle's LOAD DATA INFILE. See section 6.4.9 LOAD DATA INFILE Syntax.
ANALYZE TABLE, CHECK TABLE, OPTIMIZE TABLE, and
REPAIR TABLE statements.
SHOW statement.
See section 4.5.6 SHOW Syntax.
SET statement. See section 5.5.6 SET Syntax.
GROUP BY part.
This gives better performance for some very specific, but quite normal
queries.
See section 6.3.7 Functions for Use with GROUP BY Clauses.
ASC and DESC with GROUP BY.
|| and && operators to mean
logical OR and AND, as in the C programming language. In MySQL Server,
|| and OR are synonyms, as are && and AND.
Because of this nice syntax, MySQL Server doesn't support
the ANSI SQL || operator for string concatenation; use
CONCAT() instead. Because CONCAT() takes any number
of arguments, it's easy to convert use of the || operator to
MySQL Server.
CREATE DATABASE or DROP DATABASE.
See section 6.5.1 CREATE DATABASE Syntax.
% operator is a synonym for MOD(). That is,
N % M is equivalent to MOD(N,M). % is supported
for C programmers and for compatibility with PostgreSQL.
=, <>, <= ,<, >=,>,
<<, >>, <=>, AND, OR, or LIKE
operators may be used in column comparisons to the left of the
FROM in SELECT statements. For example:
mysql> SELECT col1=1 AND col2=2 FROM tbl_name;
LAST_INSERT_ID() function.
See section 8.4.3.130 mysql_insert_id().
REGEXP and NOT REGEXP extended regular expression
operators.
CONCAT() or CHAR() with one argument or more than two
arguments. (In MySQL Server, these functions can take any number of
arguments.)
BIT_COUNT(), CASE, ELT(),
FROM_DAYS(), FORMAT(), IF(), PASSWORD(),
ENCRYPT(), MD5(), ENCODE(), DECODE(),
PERIOD_ADD(), PERIOD_DIFF(), TO_DAYS(), or
WEEKDAY() functions.
TRIM() to trim substrings. ANSI SQL only supports removal
of single characters.
GROUP BY functions STD(), BIT_OR(), and
BIT_AND().
REPLACE instead of DELETE + INSERT.
See section 6.4.8 REPLACE Syntax.
FLUSH, RESET and DO statements.
:=:
SELECT @a:=SUM(total),@b=COUNT(*),@a/@b AS avg FROM test_table; SELECT @t1:=(@t2:=1)+@t3:=4,@t1,@t2,@t3;
We try to make MySQL Server follow the ANSI SQL standard and the ODBC SQL standard, but in some cases MySQL Server does things differently:
VARCHAR columns, trailing spaces are removed when the value is
stored. See section 1.8.5 Known Errors and Design Deficiencies in MySQL.
CHAR columns are silently changed to VARCHAR
columns. See section 6.5.3.1 Silent Column Specification Changes.
REVOKE to revoke privileges for
a table. See section 4.3.1 GRANT and REVOKE Syntax.
NULL AND FALSE will evaluate to NULL and not to FALSE.
This is because we don't think it's good to have to evaluate a lot of
extra conditions in this case.
For a prioritised list indicating when new extensions will be added to MySQL Server, you should consult the online MySQL TODO list at http://www.mysql.com/doc/en/TODO.html. That is the latest version of the TODO list in this manual. See section 1.9 MySQL and The Future (The TODO).
SELECTsSubqueries have been implemented in MySQL version 4.1. See section 1.6.1 Features Available From MySQL 4.1.
MySQL Server until version 4.0 only supports nested queries of the form
INSERT ... SELECT ... and REPLACE ... SELECT ....
You can, however, use the function IN() in other contexts.
You can often rewrite the query without a subquery:
SELECT * FROM table1 WHERE id IN (SELECT id FROM table2);
This can be rewritten as:
SELECT table1.* FROM table1,table2 WHERE table1.id=table2.id;
The queries:
SELECT * FROM table1 WHERE id NOT IN (SELECT id FROM table2);
SELECT * FROM table1 WHERE NOT EXISTS (SELECT id FROM table2
WHERE table1.id=table2.id);
Can be rewritten as:
SELECT table1.* FROM table1 LEFT JOIN table2 ON table1.id=table2.id
WHERE table2.id IS NULL;
Using a LEFT [OUTER] JOIN is generally much faster than an
equivalent subquery because the server can optimise it better,
a fact that is not specific to MySQL Server alone.
Prior to SQL-92, outer joins did not exist, so subqueries were the
only way to do certain things in those bygone days. But that is no
longer the case, MySQL Server and many other modern database
systems offer a whole range of outer joins types.
For more complicated subqueries you can often create temporary tables
to hold the subquery. In some cases, however, this option will not
work. The most frequently encountered of these cases arises with
DELETE statements, for which standard SQL does not support joins
(except in subqueries). For this situation there are two options
available:
The first option is to upgrade to MySQL version 4.1
The second option is to use a procedural programming language (such as
Perl or PHP) to submit a SELECT query to obtain the primary keys
for the records to be deleted, and then use these values to construct
the DELETE statement (DELETE FROM ... WHERE ... IN (key1,
key2, ...)).
The third option is to use interactive SQL to construct a set of
DELETE statements automatically, using the MySQL
extension CONCAT() (in lieu of the standard || operato