删除重复记录（Mysql,SqlServer,Sqlite）

Mysql中有重复的数据：

select resource_id,count(1) from t_resource_apptype_releation  GROUP BY resource_id having count(1)>1 order by count(1) desc

删除一下吧：

delete a from t_resource_apptype_releation as a,
(
select *,min(id) from t_resource_apptype_releation group by resource_id having count(1) > 1
) as b
 where a.resource_id = b.resource_id and a.id > b.id;

创建一个唯一索引，防止再发生类似事件。

 

现在开始玩SQL SERVER 

查看：

select resource_id,count(1) from t_resource_apptype_releation  GROUP BY resource_id having count(1)>1 order by count(1) desc 

删除：

delete aa from t_resource_apptype_releation aa where  exists(select * from t_resource_apptype_releation where aa.id>id and  resource_id=aa.resource_id)

Sqlite这样：

delete from T_RESOURCE_APPTYPE_RELEATION where id not in (select min(id) from T_RESOURCE_APPTYPE_RELEATION  group  by resource_id);