1、单个字段
查询所有重复数据
select * from ActivityWinUser where (UID) in(select UID from ActivityWinUser group by UID having count(*)>1);
去重
delete from table where Name in(select Name from table group by Name having count(*)>1);
2、多个字段
查询所有重复数据
select * from table a where (a.UID,a.ActivityID) in (select UID,ActivityID from table group by UID,ActivityID having count(*) > 1) ;
3、去除重复记录
select *, count(distinct name) from table group by name