1. 需求:分组后得到id =3 和id =6 的行数
![](https://img2020.cnblogs.com/blog/2007885/202011/2007885-20201119171540538-225523060.png)
2.解决(sql)
方法一:
-- 将符合条件的id 放在where条件后 SELECT id, A, B FROM test AS a WHERE id IN ( SELECT max( b.id ) AS id FROM test AS b GROUP BY b.A )
结果:
![](https://img2020.cnblogs.com/blog/2007885/202011/2007885-20201119171612796-519583757.png)
方法二
-- 将符合条件的id 作为子查询 连接自己 SELECT a.id, a.A, a.B FROM test AS a INNER JOIN ( SELECT max( b.id ) AS id FROM test AS b GROUP BY b.A ) c ON a.id = c.id
结果:
![](https://img2020.cnblogs.com/blog/2007885/202011/2007885-20201119171615866-171425694.png)