This is the MySQL reference manual. This version documents the 3.21.31 version of MySQL.
MySQL is a basically free, very fast SQL database server. See section 3 Licensing or When do I have/want to pay for MySQL?.
The latest information about MySQL is found at the MySQL Home page
To see what it can do. See section 1.4 The main features of MySQL.
For installation instructions See section 4 Compiling and installing MySQL. For tips on how to port MySQL to new machines/operating systems See section G Comments on porting to other systems..
If you have any suggestions concerning additions or corrections to this
manual, please send them to the MySQL mailing list
documentation suggestion: [Insert Topic Here].
See section 2.1 Subscribing to/un-subscribing from the MySQL mailing list..
See section 8.5.2 Upgrading to 3.21 from a 3.20 version, for information about upgrading from a 3.20 release.
For examples of SQL and benchmarking information see the `bench' directory.
For future plans See section F List of things we want to add to MySQL in the future (The TODO)..
A history of new features/bug fixes See section D MySQL change history.
For the currently known bugs/misfeatures (known errors) See section E Known errors and design deficiencies in MySQL.
For A list of all the contributors to this product See section C Who has helped to make MySQL..
IMPORTANT:
Send bug (error) reports, questions and comments to the mailing list at
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 consider a valid bug report.
The mysqlbug script can be found in the `scripts' directory in the distribution, that is `there-you-installed-mysql/scripts'.
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).
This manual is currently available in TeXInfo, Raw text, Info and HTML versions. A PostScript version as available do 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 version 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 See section B Contributed programs.
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.
FLOAT, DOUBLE, CHAR, VARCHAR,
TEXT, BLOB, DATE, DATETIME, YEAR,
SET and ENUM types. See section 7.2 Column types.
select column1 + column2 from table where column1/column2 > 0
GROUP BY and ORDER BY. Support for
group functions (COUNT, AVG, STD, SUM, MAX
and MIN).
LEFT OUTER JOIN with ANSI SQL and ODBC syntax.
autoconf for portability.
purify).
DELETE, INSERT, REPLACE, and UPDATE returns
how many rows were affected.
--help or -? for help.
show tables, SHOW INDEX FROM table and
show columns from table
There is one SQL tutor on the net at http://w3.one.net/~jhoffman/sqltut.htm
This one 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
There are also many web pages that use MySQL. See section A Some users of MySQL.. Send any additions to this list to
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 there is less data that has to 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 See section F List of things we want to add to MySQL in the future (The TODO)..
Requests to be added 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
un-subscribe mysql will suffice. If your reply address is not
valid you may use subscribe mysql your@address.your-domain or
un-subscribe mysql your@address.your-domain.
Please do not send mail about [un]subscribing to 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 mailinglists exists:
mysql-announce
mysql
mysql-digest
mysql-Java
mysql-win32
myodbc
msql-mysql-modules
msql-mysql-modules-digest
You subscribe/unsubscribe to all lists in the same way as described
above. Just exchange mysql with the list name.
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
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 anyway related to a MySQL version you are using!
mysqlbug should automaticly finds most of the following information, but if something important missing please include this in your question!
mysqladmin version.
uname -a.
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.
Since it is very hard to now why something crashing please do one of the following things.
First try to check if thigs that work for other crash for you:
--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.
back (or the backtrace command in your debugger) when
mysqld core dumps.
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.
Basic licensing issues:
See section J The MySQL server license.
For normal use MySQL costs nothing. When you sell MySQL directly or as a part of another product you have to pay for it. See section J The MySQL server license.
The client access part of MySQL is in the public domain. The command line client includes parts that is 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 |
| licenses | Price/Copy | Minimum at one time | Minimum Payment |
| 100-1000 | $40 | 100 | $4000 |
| 1000-2500 | $25 | 200 | $5000 |
| 2500-5000 | $20 | 400 | $8000 |
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:
One year of basic email support costs $200 (USD).
It includes:
One year of extended email support costs $1000 (USD).
Extended basic supports contains everything in basic email support with these additions:
BLOB or TEXT types
yet). The current server includes support to read such databases but not
the packing tool.
One year of email/phone/telnet support costs $2000 (USD).
Login supports contains everything in extended basic email support with these additions:
One year of extended email/phone/telnet support costs $5000 (USD).
Extended login supports contains everything in login support with these additions:
select my_calculation(column1,column2) from database;
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
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
There are (at least) four different copyright's on the MySQL distribution.
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
mysys, mystring and dbug libraries.
getopt) are covered by the
"GNU LIBRARY LIBRARY GENERAL PUBLIC LICENSE".
See the `mysys/COPYING.LIB' file.
readline) are covered by the
"GNU GENERAL PUBLIC LICENSE". See the `readline/COPYING' file.
regexp library) are covered by a Berkeley
style copyright.
Our philosophy behind this is:
This is a clarification of the information in the 'MySQL FREE PUBLIC LICENSE'. See section J The MySQL server license.
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:
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 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.
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).
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?
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.
You can always check MySQL's home page to read the latest news.
But since the Internet connection at TcX is not very fast we would prefer if you do the actual downloading from one of the mirrors below.
Europe:
Austria WWW [Univ. of Technology/Vienna]
Bulgaria FTP [Naturella]
Czech Republic WWW [CESNET]
Denmark WWW [Ake]
Denmark WWW [SunSITE]
Denmark FTP [SunSITE]
Estonia WWW [Tradenet]
France WWW [minet]
Germany WWW [Wolfenbuettel]
Germany WWW [Staufen]
Hungary WWW [Xenia]
Israel WWW [Netvision]
Israel FTP [Netvision]
Italy WWW [Matrice]
Poland WWW [Sunsite]
Poland FTP [Sunsite]
Portugal WWW [Telenet]
Russia FTP [Cityline]
Romania WWW [Timisoara]
Romania FTP [Timisoara]
Romania WWW [Bucharest]
Romania FTP [Bucharest]
Sweden WWW [Sunet]
Sweden FTP [Sunet]
UK WWW [Omnipotent/UK]
UK FTP [Omnipotent/UK]
UK WWW [PLiG/UK]
UK FTP [PLiG/UK]
North America:
Canada WWW [Polaris Computing]
Canada WWW [Tryc]
Canada WWW [Cyberus]
Canada FTP [Cyberus]
USA WWW [Hurricane Electric/San Jose]
USA WWW [Buoy/New York]
USA WWW [Hypernet Communications/Dallas]
USA WWW [Hurricane Electric/California]
USA FTP [Netcasting/West Coast]
USA WWW [Savages/Oregon]
USA WWW [Circle Net/North Carolina]
USA WWW [Gina net/Florida]
USA FTP [DIGEX]
Asia:
Korea WWW [KREONet]
Japan WWW [HappySize]
Japan FTP [HappySize]
Singapore WWW [Com5 Productions]
Singapore FTP [Com5 Productions]
Taiwan WWW [NCTU]
Australia:
The first decision is if 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. See section 11 MySQL benchmark suite.
The second decision is if you want a source 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.
Note that all releases have at least been tested with:
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.
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.
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.
What you need:
gzip to uncompress the distribution.
tar to unpack the distribution. GNU tar is
known to work.
C++ compiler. gcc >= 2.7, SGI C++, SunPro C++ are
some of the compilers that are known to work. libg++ is not
needed when using gcc.
make program. If you have problems we recommend trying GNU
make.
Unpack tar archive in a directory. The tar file should be named like mysql-VERSION.tar.gz (VERSION is a number like 3.21.31). A directory named mysql-VERSION should be created.
zcat mysql-VERSION.tar.gz | tar xvf -
cd mysql-VERSION
./configure
make
make install
./scripts/mysql_install_db
'installation_directory'/bin/mysqladmin version
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 doing a new configure!
GNU make is always recommended and is sometimes required.
--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 compile with --without-server. Ignore in
this case any warnings about mysql.cc (The only MySQL client
that needs C++).
--prefix=/usr/local or --prefix=/usr/local
--localstatedir=/usr/local/data/mysql
--with-unix-socket-path=absolute_file_name
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.
LDFLAGS=-static ./configure.
CC=gcc CXX=gcc ./configure
DEFAULT values at all and you want to get
an error for an INSERTs that doesn't use all NOT NULL columns
configure with CXXFLAGS=-DDONT_USE_DEFAULT_FIELDS ./configure.
--with-charset=charset.
Where [charset] may be one of: big5, czech, dec8,
dos, german1, hp8, koi8_ru, latin1,
latin2, swe7, usa7, ujis, or sjis.
See section 9.1.1 Character set used for data & sorting.
If you want to convert characters between the server and the client,
you should take a look at the SET OPTION CHARACTER SET.
See section 7.20 SET OPTION syntax.
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 incorecctly in some cases (but
not all!).
Some times 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.
If your compile fails with something like:
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 nead to have libg++ installed!
If you have any problems with using g++, or libg++ or libstdc++, you can probably always solve these by configuring as above!
You can also install libg++. By default `configure' picks
c++ as a compiler name and GNU c++ links with
-lg++.
making all in mit-pthreads make: Fatal error in reader: Makefile, line 18: Badly formed macro assignmentThis means you have to upgrade your make to GNU
make.
CC="gcc -O4" CXX="gcc -O4" export CC CXX
make stops with Can't find Makefile.PL when
you should try using GNU make. Solaris and FreeBSD
are known to have troublesome make programs.
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).
client/libmysql.c:273: parse
error before `__attribute__'
This means you need to upgrade your gcc compiler (2.7.2 is known to work).
mysqlbug
when posting questions to mysql@tcx.se. See section 2.3 I think I have found a bug. What information do you need to help me?.
Even if the problem isn't a bug, mysqlbug gathers some system
information that will help others solve your problem!
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_DEBUGYou will now get a trace file in `/tmp/client.trace'.
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
after 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.
mysql --debug=d:t:o,/tmp/client.trace before mailing a bug
report. See section 2.3 I think I have found a bug. What information do you need to help me?.
All MySQL programs compile clean (no warnings) for us (on Solaris using gcc). But warning may appear because of different system include files. Se 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 yacc). Normally you don't have to do this as MySQL comes with a already compiled sql_yacc.cc file.
If you want to have static linked code, use (with gcc):
LDFLAGS="-static" ./configure ...
You can on most systems 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-threads. This is because we want to keep our changes to this code minimal.
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 (-h or
--host) switch to mysql. This must be done if you have
compiled the client code --without-server because the default
connection is to use Unix sockets.
MySQL compiled with MIT threads has system locking 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 of this is
that all connections to server fails.
> 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-threads. 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 got readline to work with MIT threads. (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(...)'
The included perl client code requires perl5.004 or later.
If you got a 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 build (check the output for mysql.so when you
compile the perl client).
-L/... is the path to the directory where libgcc.a
exists.
Another problem may be that perl and MySQL isn't both compiled with gcc. In this case you can solve this by compile 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).
Sun native threads only work on Solaris 2.5 and higher. For 2.4 and earlier versions, you can use MIT-pthreads. See section 4.8 MIT-pthreads notes. (FreeBSD).
If there are too many processes that try to connect very rapidly to the
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 row in configure:
#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 egcs or gcc version and compile this 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 possible other programs!)
The tar in Solaris 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 copy of precompiled gnu tar (gtar) for Solaris at http://www.mysql.com/Downloads/
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.
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 because 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 library. There is a lot of simple workarounds to get MySQL to work! The simplest is to use the binary version (not the RPM) of MySQL for Linux x86; One nice aspect of this version is that it's probably 10% faster than any version you would compile yourself! See section 10.2 How compiling and linking affects the speed of MySQL
When using LinuxThreads you will see a minimum of three processes running. These are in fact threads. There will be one thread for the Linux Threads 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.
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 has been some problems with the glibc rpms from RedHat so if you have problems, check if there are any updates!
On some older Linux distributions configure may give a error
about: 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 says and add a 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'
If you want in Debian GNU/Linux to get MySQL to auto start when 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.
If you install all the official redhat patches (including glibc-2.0.6-9 and glibc-devel-2.0.6-9) it should work out of the box (se 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 static-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 a wrong glibc or linuxthread version the symptom is that
mysqld crashes after each connections. For example mysqladmin version
will crash mysqld when it finishes!
Another symptom of wrong 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
new versions as glibc 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 compiled staticly to avoid library conflicts and should work on all Linux systems!
If you want to compile this yourself, check how to debug mysqld! As MySQL comes with an internal debugger its very easy to get a trace file that probably will help solve your problem very quickly! See section 18.10 Debugging MySQL
In some implementations readdir_r is broken. This will be
noticed when 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 Lf 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.
The first problem is linuxthreads. You must patch linuxthreads for alpha because the RedHat distribution uses an old (broken) linuxthreads version.
CC=gcc CCFLAGS="-Dalpha_linux_port" CXX=gcc CXXFLAGS="-O3 -Dalpha_linux_port" ./configure --prefix=/usr/local/mysql
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.
When compiling threaded programs under Digital UNIX using CC / CXX the
documentation recommends the 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 will may 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 directly. If so, try
starting it with nohup safe_mysqld [options]
nohup is a command that ignores any SIGHUP sent from the
terminal.
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 appears also 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 from OSF 4.0C:
CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql
In some versions of OSF1, the alloca() functions is broken. Fix
this by removing 'HAVE_ALLOCA' from config.h.
The alloca() function can also have a wrong prototype in
/usr/include/alloca.h. This warning can be ignored.
Configure will automaticly use the following thread libraries:
-with-named-thread-libs="-lpthread -lmach -lexc -lc"
When using gcc you can also try to use:
CFLAGS=-D_PTHREAD_USE_D4 CXX=gcc CXXFLAGS=-O3 ./configure ....
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 selects, remove HAVE_ALLOC &
HAVE_ALLOCA_H from `config.h'. If mysqladmin create doesn't
work, remove HAVE_READDIR_R from config.h. Also you may have to
remove HAVE_TERM_H.
Irix 6.2 doesn't support POSIX threads out of of the box. You have install these patches, 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. This is because 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 line:
CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql --with-thread-safe-client
If you get a error on 'make install' that it can't find /usr/include/pthreads, configure didn't detect that one neads mit-threads on FreeBSD. This is fixed by doing:
rm config.cache ./configure --with-mit-threads
If you get link errors when compiling mysqlperl (Type
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:
CFLAGS = -g -O2 to
CFLAGS = -O2 -DPIC -fpic
cd client
rm *.o
make libmysqlclient.a
cd ../perl
make
This shall hopefully be handled automatically in the future.
The FreeBSD make behaviour is slightly different from 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 ine 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. See section 15.7 File not found
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 (else you will have problems
connecting to the database).
If you are using FreeBSD 2.2.26:
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.
You have to configure with:
--with-named-thread-libs=-lc_r
The pthreads library for FreeBSD doesn't contain the sigwait
function and there is 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. Follow after this 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.
From Jan Legenhausen jleg@csl-gmbh.net.
I finally got mysqlperl working on BSDI2.1.
What i did was almost nothing:
GCC="shlicc2" per default;
perl5 automagically uses shlicc2 - you should use _one_ version (either
gcc or shlicc2) for both Mysql.c and
libmysqlclient.a!)
rm *.o
gmake libmysqlclient.a
cd ../perl/mysqlperl
make clean
$sysliblist=" -L$tmp -lgcc -lcompat"; to Makefile.PL line 45
(just to be sure - i didn't check if one could leave out this one)
perl Makefile.PL
libmysqlclient.a's in /usr/lib and
/usr/contrib/lib
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.
env CXX=shlicc++ CC=shlicc2 ./configure --prefix=/usr/local/mysql --localstatedir=/var/mysql --without-perl --with-unix-socket-path=/var/mysql/mysql.sockThe following is also known to work:
env CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql --with-unix-socket-path=/var/mysql/mysql.sock
You can change the directory locations if you wish, or just use their defaults by not specifying them.
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'.
as.
make when making MySQL.
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-perlYou 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:
-lgthreads -lsocket -lgthreads
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.
There is a couple of 'small' problems when compiling mysql on HPUX. Below we describe some problems and workarounds when using the HPUX compiler and gcc 2.8.0 .
gcc 2.8.0 can't compile readline on HPUX (internal compiler error). mit-pthreads can't be compiled with HPUX compiler, because it can't compile .S (assembler) files.
We got MySQL to compile on HPUX 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
The MySQL-win32 version has by now proven itself to be very stable. The MySQL-win32 version has all the features as the corresponding Unix version of MySQL with the following exceptions:
ALTER TABLE
ALTER TABLE on file if it is hold 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
Win95 and threads
Other win32 specific issues are described in the README file that comes with the MySQL-win32 distribution.
Please always use the mysqlbug script when posting questions to the mailinglist (mysql@tcx.se). Even if the problem isn't a bug, mysqlbug gathers some system information that will help other solve your problem! See section 2.3 I think I have found a bug. What information do you need to help me?.
> cd /usr/local > zcat /<where ever you put it>/mysql-3.20.0-SunOS5.tgz | tar xvf - > ln -s mysql-VERSION mysql
> scripts/mysql_install_dbSee section 4.13 Problems running 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.
> bin/safe_mysqld --log &
> bin/mysqladmin verThat 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
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:
/usr/local/mysql)
/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.
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-assemblerAll of the above is typed as one long line!
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.
Clients have to be linked with: -lmysqlclient
The default priviliges is that anybody may create/use the databases
named test or starting with test_. root can do
anyting. See section 6.2 How does the privilege system work?.
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 privilige
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.
Installing a second mysqld daemon doesn't work when one daemon is running.
MYSQL_UNIX_PORT=/tmp/mysqld-new.sock MYSQL_TCP_PORT=3307 export MYSQL_UNIX_PORT MYSQL_TCP_PORT scripts/mysql_install_dbAfter 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.
MySQL mail archives.
See section 4.10.3 Linux notes for all versions
Can't connect to the server (when using mit-threads)
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 localhostThe above is only a problem on system that doesn't have a thread library and MySQL has to use mit-threads.
You don't have write access to create a socket file (in /tmp ?)
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 mysqlAfter this you can execute the sql commands in mysql_install_db.
The paths may be different from what mysqld expects.
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
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 sometimes decide to upgrade 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.
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.
MEDIUMINT, SET, ENUM and the
different BLOB and TEXT types.
AUTO_INCREMENT, BINARY,
UNSIGNED and ZEROFILL.
BINARY attribute.
INTO OUTFILE and STRAIGHT_JOIN in a SELECT
statement. See section 7.10 SELECT syntax.
EXPLAIN SELECT to get a description on how tables are joined.
INDEX or KEY in a CREATE TABLE
statement. See section 7.6 CREATE TABLE syntax.
DROP column or CHANGE column in an ALTER TABLE
statement. See section 7.7 ALTER TABLE syntax.
LOAD DATA INFILE. This syntax is in many cases compatible with
Oracle's LOAD DATA INFILE. See section 7.14 LOAD DATA INFILE syntax.
" instead of ' to enclose strings.
\ character.
SET OPTION statement. See section 7.20 SET OPTION syntax.
GROUP BY part.
See section 7.3.12 Functions for GROUP BY clause.
|| 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.
CREATE DATABASE or DROP DATABASE.
See section 7.4 Create database syntax.
% instead of mod(). % is supported for C programmers and
for compatibility with PostgreSQL.
=, <>, <= ,<, >=,>, AND,
OR, or LIKE in a column statement
LAST_INSERT_ID.
See section 17.1.3 How can I get the unique ID for the last inserted row?
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().
TRIM to trim substrings. ANSI SQL only supports removal
of single characters.
STD(), BIT_OR and BIT_AND group functions.
MIN() or MAX() as normal functions, not only group
functions.
REPLACE instead of DELETE + INSERT.
See section 7.13 REPLACE syntax
The following functionality is missing in the current version of MySQL. For the priority of new extensions you should consult: The MySQL Todo list. That is the latest version of the Todo list in this manual. See section F List of things we want to add to MySQL in the future (The TODO)..
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.
MySQL doesn't yet support SELECT ... INTO TABLE.... Currently
MySQL only supports SELECT ... INTO OUTFILE..., which is basicly the
same thing..
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.
See section 7.19 LOCK TABLES syntax
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.
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.
There are so many problems with the FOREIGN KEYs that we don't
know where to start.
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.
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.
MySQL doesn't support views, but this is on the TODO.
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.
See section 7.24 Comment syntax
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 automaticly 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
Entry level SQL92. ODBC level 0-2.
GRANT. See section 7.21 GRANT syntax. (Compatibility function). This always succeeds. You should use the
MySQL privilege tables. See section 6.2 How does the privilege system work?
CREATE INDEX. See section 7.22 CREATE INDEX syntax (Compatibility function). This always succeeds. You
should create your index with CREATE TABLE. See section 7.6 CREATE TABLE syntax.
You can also use ALTER TABLE. See section 7.7 ALTER TABLE syntax.
DROP INDEX. See section 7.23 DROP INDEX syntax (Compatibility function). This always succeeds. You can use
ALTER TABLE to drop indexes. See section 7.7 ALTER TABLE syntax.
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);
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