oracle删除重复记录保存一条

最快的方法是用row_number() over (partition by  关键字 order by ...) 
删除序号大于1的，这个方法经过实践后，速度最快，而且代码容易理解，完整代码是：


delete from 表 where ROWID in (         
select   RID from （select  ROWID as RID, row_number() over (partition by 关键字 order by  rowid) as rn  from 表) a
  where a.rn>1
）

eg：

delete from t_identify_relevance_temp where ROWID in (         
select   RID from (select  ROWID as RID, row_number() over (partition by prod_inst_num,identify_id,cust_id order by  rowid) as rn  from t_identify_relevance_temp) a
  where a.rn>1
)