Oracle

Posted 2020-08-20 学习是不让自己瞎想的最好方式

去除表中存在的重复数据：

DELETE from 表 WHERE (cert_no) IN

( SELECT cert_no FROM 表 GROUP BY cert_no HAVING COUNT(cert_no) > 1)

 AND ROWID NOT IN (SELECT MIN(ROWID) FROM 表 GROUP BY cert_no HAVING COUNT(*) > 1);

 

查询及删除重复记录的SQL语句

 

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)