数据库

查询某个数据库中的所有表 ：

select * from sysobjects where xtype='u';

 

 

查询某个表的表结构：

select col.[name] as '字段名',
         col.[length] as '长度',
         type.[name] as '类型',
         pro.value as '描述'
from syscolumns as col
left join Systypes as type on col.xtype=type.xtype
left join SysProperties as pro on col.id=pro.id and col.colid=pro.smallid
where col.id=(select id from Sysobjects where name='要查询的表名');

 

 

随机选择记录：

select newid();

 

随机读取若干条记录：[ ------>n表示要取出的数据行数]

sqlserver------>:     select top n * from 表名 order by newid();       

mysql--------->:     select * from 表名 order by rand() limit n;