1.用子查询：
SELECT * FROM tableName a WHERE 3>
(SELECT COUNT(*) FROM
tableName b WHERE b.id=a.id AND b.cnt>a.
cnt)
ORDER BY a.id,a.account DESC
2.用exists半连接：
SELECT * FROM
tableName a WHERE EXISTS
(SELECT COUNT(*) FROM
tableName b WHERE b.id=a.id AND a.account<b.
cnt HAVING COUNT(*)<3)
ORDER BY a.id,a.
cntDESC
二、同理可以取组内最小的N条记录：
例如：取每组的前3条最小的记录
１、子查询
SELECT * FROM
tableName
a WHERE 3>
(SELECT COUNT(*) FROM
tableName
b WHERE b.id=a.id AND b.
cnt<a.
cnt)
ORDER BY a.id,a.
cnt DESC
２、用exists：
SELECT * FROM
tableName
a WHERE EXISTS
(SELECT COUNT(*) FROM
tableName
b WHERE b.id=a.id AND a.
cnt>b.
cnt HAVING COUNT(*)<3)
ORDER BY a.id,a.
cnt DESC