1. Oracle,随机查询20条

select * from 

( 
 select  *  from 表名
 order by dbms_random.value 

)
 where rownum <= 20; 

 

2.MS SQL Server，随机查询20条

select top 20  * from  表名order by newid()

 

3.My SQL:，随机查询20条

select  *  from  表名 order by rand() limit 20

?