oracle 删除重复记录

语法：

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);

 后续：当然也可以DELETE from 表 WHERE (id,rowid) IN ( SELECT id,min(rowid) FROM 表 GROUP BY id HAVING COUNT(id) > 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)
后续：当然也可以：

 delete from 表 a where (a.Id,a.seq,rowid) in (select Id,seq ,max(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)


测试：
create global temporary table test2(name varchar2(100))
on commit preserve rows;

truncate table test2;
insert into test2 values('wei1');
insert into test2 values('wei1');
insert into test2 values('wei2');
insert into test2 values('wei2');
insert into test2 values('wei3');
insert into test2 values('wei3');
insert into test2 values('wei4');


delete from test2
where name in(select name from test2 d2 group by name having count(*)>1 )
and rowid  in(select min(rowid) from test2 group by name having count(*)>1);

select name, rowid  from test2;