Oracle 删除重复数据只留一条

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

例如：

（1）查询部位表的多余的数据 （根据 code ）

select count(1) from base_part where code in (select code from base_part group by code having count(code) > 1);

（2）删除多余的数据，只留 rowid 最小的记录

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