MySQL: Difference between revisions

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'''MySQL''' is a very fast, multi-threaded, multi-user and robust [[SQL]] (Structured Query Language) [[relational database]] server. MySQL is [[free software]]: it is licensed under the [[GNU General Public License]]. It was written and is maintained by the Swedish company MySQL AB, which sells support and service contracts as well as commercially licensed copies of MySQL and employs people all over the world who communicate over the internet. [[MySQL AB]] was set up by two Swedes and a Finn: [[David Axmark]], [[Allan Larsson]] and [[Michael "Monty" Widenius]]. Despite the widespread pronunciation of SQL being "sequel", the generally accepted pronunciation of MySQL by professionals is "My ess-que-ell", not "My-Sequel".

=== Platforms ===

MySQL is open source and works on many different platforms including [[AIX operating system|AIX]], [[BSDi]], [[DEC Unix]], [[FreeBSD]], [[HP-UX]], [[Linux]], [[Mac OS X]], [[NetBSD]], [[OpenBSD]], [[OS/2]] Warp, [[SGI]] [[Irix]], [[Solaris Operating Environment|Solaris]], [[SunOS]], SCO OpenServer, SCO UnixWare, [[Tru64 Unix]], [[Microsoft Windows|Windows]] 95, 98, NT and 2000.

=== Programming Languages ===

MySQL databases can be accessed using the [[programming language|programming languages]] [[C programming language|C]], [[C Plus Plus|C++]], [[Eiffel programming language|Eiffel]], [[Java programming language|Java]], [[Perl]], [[PHP]], [[Python programming language|Python]], and [[Tcl]]; for each of these, a specific [[API]] is available. An [[ODBC]] interface called MyODBC is also available.

=== Early versions ===

The full [[ANSI SQL]] standard is extended in some areas and not implemented in others; probably the most often requested features which are not yet implemented are:

OtherEarly standardversions SQL featuresof MySQL hasincluded notfew implementedstandard includeDBMS [[referentialfeatures integrity]](transactions, stored constraintsprocedures), and [[stored procedure]]s.lead Somesome database experts including [[Christopher J. Date|Chris Date]] and [[Fabian Pascal]] haveto criticizedcriticize MySQL, particularly for the lack of transactions, as well as enforced integrity constraints, which in other DBMSes allow the database system to ensure that applications cannot insert inconsistent values. [http://www.dbdebunk.com/]

* "Sub-SELECTs" or "nested SELECTs". The MySQL website states that "Subselects are currently being implemented in the 4.1 development tree."

=== The latest production version ===

The latest production version is 4.0. It includes the following features:

* A broad subset of ANSI SQL 99, as well as extensions.

* Cross-platform support

* Independent storage engines (MyISAM for read speed, InnoDB for transactions and referential integrity)

* Transactions

* SSL Support

* Query caching

* Replication

* Full-text indexing and searching

* Embedded database library

It does not include the following features:

* Sub-SELECTs (or nested SELECTs)

* multibyte character encoding or [[Unicode]]/[[UTF-8]]

* Stored procedures

=== The development version ===

Version 4.1 is the development version, and includes support for the following features:

* Sub-SELECTS

* UTF-8

* Support for geographical data (OpenGIS)

* Derived tables

* Multi-line queries

=== Future releases ===

MySQL 5.0 will contain support for the following features:

* Stored procedures

* Triggers

* Cursors

* True VARCHAR support

* Easier GIS access

MySQL 5.1 will contain support for:

A development version of MySQL 4.1, containing support for "Sub-SELECTs" was released in January 2003. Version 4.1 also contains support for UTF-8. MySQL originally lacked support for [[transaction|transactions]], however this feature is now available.

* Foreign key support for all table types

* Online backup

* Fail-safe replication

* Column-level constraints

MySQL 6.0 will contain support for views.

Other standard SQL features MySQL has not implemented include [[referential integrity]] constraints and [[stored procedure]]s. Some database experts including [[Christopher J. Date|Chris Date]] and [[Fabian Pascal]] have criticized MySQL particularly for the lack of enforced integrity constraints, which in other DBMSes allow the database system to ensure that applications cannot insert inconsistent values. [http://www.dbdebunk.com/]

=== Wikipedia on MySQL ===

In [[August 2001]], a test version of the [[Wikipedia]] software using [[PHP programming language|PHP]] and MySQL appeared; in January 2002 it was adopted as the new software running Wikipedia. See the [[wikipedia:PHP script|Wikipedia PHP script]] page. In May 2003, this code base was [[m:Upgrade to MySQL 4.0|upgraded to MySQL version 4.0.12]] from the previous version 3.x.

See also: [[PostgreSQL]], [[Berkeley DB]]

=== External links:===
* MySQL web site at [http://www.mysql.com]

* MySQL roadmap [http://www.databasejournal.com/features/mysql/article.php/2210771]

* Database Debunking [http://www.dbdebunk.com/]