Person表Id Email 两个字段
要求写语句把有Email重复的记录 保留Id最小的一个 其他删除
1.2区别在于select * 1是正确答案 2是我的想法
请问各位大神 这里的select * from到底作用是什么
delete from Person where Id not in
(select * from (
select min(Id) from Person group by Email )as t
)
delete from Person where Id not in
(select min(Id) from Person group by Email)as t