Oracle 学习笔记

查询及删除重复记录的 SQL 语句

一、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)

二、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);

三、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)

四、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)

五、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)