mysql删除表中重复数据创建唯一索引。

保留最小id
delete a.* from table_a as a,( select min(id) id , xx,yy from table_a group by xx,yy having count(1)>1
) as b where a.yy=b.yy and a.xx=b.xx and a.id > b.id;

保留最大id
delete a.* from table_a as a,( select max(id) id , xx,yy from table_a group by xx,yy having count(1)>1
) as b where a.yy=b.yy and a.xx=b.xx and a.id < b.id;

mysql删除表中重复数据创建唯一索引。

原文：https://blog.51cto.com/liuminkun/2370360