ORACLE 删除重复记录

通过几种方法的比较这种效果不错，留记之。

delete from T_YWM_ZK

　　where z  in (select z from T_YWM_ZK group by z
　　having count(z) > 1)
　　and rowid not in (select min(rowid) from T_YWM_ZK group by z having count(z )>1)