1. Oracle,随机查询查询语句-20条
select * from
(
select * from 表名
order by dbms_random.value
)
where rownum <= 20;
2.MS SQL Server，随机查询语句-20条
select top 20 * from 表名order by newid()
3.My SQL:，随机查询语句-20条
select * from 表名 order by rand() limit 20
原文：http://www.cnblogs.com/mafeng/p/5869607.html