系统数据库 information\_schema存储着所有的数据库的相关信息  例： ``` select schema_name from information_schema.schemata; select table_name from information_schema.schemata where table_schema = 'zzcms'; select column_name from information_schema.columns where table_schema = 'zzcms' and 'table_name' = 'zzcms_zx'; ```