这是关于5.1版至5.1.2-alpha版MySQL数据库系统的参考手册。该手册不适用于旧版本MySQL软件，这是因为在MySQL 5.1和以前的版本存在很多功能性差异和其他差异。如果正在使用MySQL软件的较旧版本，请参阅MySQL 5.0参考手册，该手册涵盖了MySQL 5.0，或参阅MySQL 4.1参考手册，该手册涵盖了MySQL 4.1以及MySQL的所有早期版本。在手册的文本中，通过引用发布版本号（5.1.x），注明了MySQL 5.1的二级版本。-This is a reference manual for version 5.1 to 5.1.2-alpha version of the MySQL database system. The manual does not apply to older versions of MySQL software, this is because there are many functional and other differences between MySQL 5.1 and previous versions. If you are using an older version of the MySQL software, please refer to the MySQL 5.0 Reference Manual, the manual covers MySQL 5.0, or see the MySQL 4.1 Reference Manual, the manual covers MySQL 4.1 and MySQL, all earlier versions. Text of the manual by reference to release numbers (5.1.x) indicate the two versions of MySQL 5.1.