1、删除orcale重复数据，
delete from da_door a
where (a.dt,a.key1) in (select dt,key1 from da_door group by dt,key1 having count(*) > 1)
and rowid not in (select min(rowid) from da_door group by dt,key1 having count(*)>1)
原文：http://www.cnblogs.com/zrlhss/p/4613330.html