SQL去重

1、單個字段

查詢所有重復數據

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、多個字段

查詢所有重復數據

select * from table a where (a.UID,a.ActivityID)  in (select UID,ActivityID from table group by UID,ActivityID having count(*) > 1) ;

3、去除重復記錄

select *, count(distinct name) from table group by name