Oracle 删除重复数据只留一条

查询及删除重复记录的SQL语句

转自： http://www.cnblogs.com/252e/archive/2012/09/13/2682817.html 

 

1、查找表中多余的重复记录，重复记录是根据单个字段（Id）来判断

 

select * from 表 where Id in (select Id from 表 group byId having count(Id) > 1)

 

 

2、删除表中多余的重复记录，重复记录是根据单个字段（Id）来判断，只留有rowid最小的记录

 

DELETE from 表 WHERE (id) IN ( SELECT id FROM 表 GROUP BY id HAVING COUNT(id) > 1) AND ROWID NOT IN (SELECT MIN(ROWID) FROM 表 GROUP BY id HAVING COUNT(*) > 1);

 

 

3、查找表中多余的重复记录（多个字段）

 

select * from 表 a where (a.Id,a.seq) in(select Id,seq from 表 group by Id,seq having count(*) > 1)

 

 

4、删除表中多余的重复记录（多个字段），只留有rowid最小的记录

 

delete from 表 a where (a.Id,a.seq) in (select Id,seq from 表 group by Id,seq having count(*) > 1) and rowid not in (select min(rowid) from 表 group by Id,seq having count(*)>1)

 

 

5、查找表中多余的重复记录（多个字段），不包含rowid最小的记录

 

select * from 表 a where (a.Id,a.seq) in (select Id,seq from 表 group by Id,seq having count(*) > 1) and rowid not in (select min(rowid) from 表 group by Id,seq having count(*)>1)

 

 

例如：

 

 服务关系表，  SERVICE_ID RELATE_ID RELATE_TYPE  三个合起来作主键，由于最初表没有建主键存在重复数据.

select * from ops_service_relate a where (a.SERVICE_ID,a.RELATE_ID,a.RELATE_TYPE) in (select SERVICE_ID,RELATE_ID,RELATE_TYPE from ops_service_relate group by SERVICE_ID,RELATE_ID,RELATE_TYPE having count(*) > 1) and rowid not in (select min(rowid) from ops_service_relate group by SERVICE_ID,RELATE_ID,RELATE_TYPE having count(*)>1)

delete from ops_service_relate a where (a.SERVICE_ID,a.RELATE_ID,a.RELATE_TYPE) in (select SERVICE_ID,RELATE_ID,RELATE_TYPE from ops_service_relate group by SERVICE_ID,RELATE_ID,RELATE_TYPE having count(*) > 1) and rowid not in (select min(rowid) from ops_service_relate group by SERVICE_ID,RELATE_ID,RELATE_TYPE having count(*)>1);