mysql_取分组后的前几行值
--方法一: select a.id,a.SName,a.ClsNo,a.Score from Table1 a left join Table1 b on a.ClsNo=b.ClsNo and a.Score<b.Score group by a.id,a.SName,a.ClsNo,a.Score having count(b.id)<2 order by a.ClsNo,a.Score desc --方法二: select * from Table1 a where 2>(select count(*) from Table1 where ClsNo=a.ClsNo and Score>a.Score) order by a.ClsNo,a.Score desc --方法三: select * from Table1 a where id in (select id from Table1 where ClsNo=a.ClsNo order by Score desc limit 2) order by a.ClsNo,a.Score desc