表中数据如下：
id uname uage
1 mickey 18
2 mickey 19
3 bob 18
4 lucy 17
要求查询出uname重复的记录
select
id,
uname,
uage
from
Users
where uname in( select uname from Users group by uname having COUNT(uname)>1 )
原文：https://www.cnblogs.com/25miao/p/9879086.html