sql语句中的information_schema.COLUMNS 是什么意思呢
的有关信息介绍如下:information_schema 是mysql数据库中的系统库,里面存放了,用户所创建的数据库和表的信息这条sql是用来查询student_info 有多少列mysql> use information_schema;mysql> show tables;可以看到下面有很多表,分别用来存放各种用户创建的信息CHARACTER_SETSCOLLATIONSCOLLATION_CHARACTER_SET_APPLICABILITYCOLUMNSCOLUMN_PRIVILEGESENGINESEVENTSFILESGLOBAL_STATUSGLOBAL_VARIABLESKEY_COLUMN_USAGEPARTITIONSPLUGINSPROCESSLISTREFERENTIAL_CONSTRAINTSROUTINESSCHEMATASCHEMA_PRIVILEGESSESSION_STATUSSESSION_VARIABLESSTATISTICSTABLESTABLE_CONSTRAINTSTABLE_PRIVILEGESTRIGGERSUSER_PRIVILEGESVIEWSFALCON_RECORD_CACHE_SUMMARYFALCON_SYSTEM_MEMORY_DETAILFALCON_SYSTEM_MEMORY_SUMMARYFALCON_SYNCOBJECTSFALCON_RECORD_CACHE_DETAILFALCON_TRANSACTION_SUMMARYFALCON_DATABASE_IOFALCON_TRANSACTIONSFALCON_SERIAL_LOG