这样的sql语句怎么实现 (分组找出组内前3)

蓝寅舞九天

周末刷论坛玩吧。。
SELECT   a.ver,a.kid,a.mid
FROM  test a inner join
test b on a.ver =b.ver and a.kid=b.kid and a.mid<=b.mid
group by a.ver,a.kid,a.mid
having count(*)<=3
order by a.ver, a.kid desc, a.mid desc
;