我将仇恨写在冰上，然后期待太阳的升起。------加西亚马尔克斯

打开mysql官方文档：Information Functions

可以看到mysql查询库表信息的函数

| Name | Description | |------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------| | BENCHMARK() | Repeatedly execute an expression | | CHARSET() | Return the character set of the argument | | COERCIBILITY() | Return the collation coercibility value of the string argument | | COLLATION() | Return the collation of the string argument | | CONNECTION_ID() | Return the connection ID (thread ID) for the connection | | CURRENT_ROLE() | Return the current active roles | | CURRENT_USER(), CURRENT_USER | The authenticated user name and host name | | DATABASE() | Return the default (current) database name | | FOUND_ROWS() | For a SELECT with a LIMIT clause, the number of rows that would be returned were there no LIMIT clause | | ICU_VERSION() | ICU library version | | LAST_INSERT_ID() | Value of the AUTOINCREMENT column for the last INSERT | | ROLES_GRAPHML() | Return a GraphML document representing memory role subgraphs | | ROW_COUNT() | The number of rows updated | | SCHEMA() | Synonym for DATABASE() | | SESSION_USER() | Synonym for USER() | | SYSTEM_USER() | Synonym for USER() | | USER() | The user name and host name provided by the client | | VERSION() | Return a string that indicates the MySQL server version |

除了USER、VERSION、LAST_INSERT_ID以外等常用函数还有DATABASE

这个可以用于获取当前USE的数据库

例如获取当前数据库中的所有表，sql如下：

|-----------|-----------------------------------------------------------------------------------------------------| | 1 | hljs mysql select * from information_schema.tables where table_schema = (select database()); |

这些函数常用的场景如代码生成器和数据库备份维护应用等