Oracle 重复数据查询以及删除

发布时间：2020-12-12 15:20:03 所属栏目：百科来源：网络整理

导读：Create table test (id number(2), names varchar2(20)); insert into test values(1,'张三'); insert into test values(2,'李四'); insert into test values(3,'马七'); select * from test; --查找重复数据 select * from test a where (a.id,a.names) in

Create table test
(id number(2),
names varchar2(20));
insert into test values(1,'张三');
insert into test values(2,'李四');
insert into test values(3,'马七');
select * from test;
--查找重复数据
select * from test a where (a.id,a.names) in
(select id,names from test group by id,names having count(*) > 1)
--删除重复数据，只留rowid最小的那行；
delete from test a where (a.id,a.names) in
(select id,names having count(*) > 1)
and rowid not in (select min(rowid) from test group by id,names having count(*)>1)
--查找重复数据，不含rowid最小的行
select * from test a where (a.id,a.names) in
(select id,names having count(*) > 1)
and rowid not in (select min(rowid) from test group by id,names having count(*)>1)

---1.以上是重复数据根据多列来判断

以下是重复数据根据单列来判断

1、首先，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 test where id in(select id from test group by 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 test where (id) in (select id from test group by id having count(id) >1) and rowid not in (select min(rowid) from test group by id having count(*)>1)

（编辑：李大同）

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