oracle删除重数据方法

前期准备
创建测试表

create table salary(

staffid int,

staff varchar(15)

);

模拟重复数据

insert into salary values(1,‘a’);

insert into salary values(2,‘s’);

insert into salary values(3,‘ert’);

insert into salary values(4,‘d’);

insert into salary values(5,‘b’);

insert into salary values(1,‘a’);

insert into salary values(2,‘s’);

insert into salary values(3,‘ert’);

insert into salary values(4,‘d’);

insert into salary values(5,‘b’);

insert into salary values(1,‘a’);

insert into salary values(2,‘s’);

insert into salary values(3,‘ert’);

insert into salary values(4,‘d’);

insert into salary values(5,‘b’);

insert into salary values(10,‘aaaa’);

insert into salary values(20,‘sass’);

insert into salary values(30,‘erwt’);

insert into salary values(40,‘dsd’);

insert into salary values(50,‘bsdf’);

insert into salary values(1,‘oookkk’);

实验一：模拟单个字段数据重复

select * from salary;

STAFFID STAFF

---

          1 oookkk

          1 a

          2 s

          3 ert

          4 d

          5 b

          1 a

          2 s

          3 ert

          4 d

          5 b

          1 a

          2 s

          3 ert

          4 d

          5 b

         10 aaaa

         20 sass

         30 erwt

         40 dsd

         50 bsdf

21 rows selected

1.查出重复数据

方法一

SELECT *

FROM salary a

WHERE ((SELECT COUNT(*)

      FROM salary

      WHERE staffid = a.staffid) > 1)

ORDER BY staffid

方法二

select *

from salary

where staffid in

(select staffid from salary group by staffid having count(staffid) > 1)

删除重复数据，只保留1条，其余全部删除

方法一，通过rowid删除

delete from salary

where staffid in (select staffid from salary group by staffid having count(staffid) > 1)

and rowid not in (select min(rowid) from salary group by staffid having count(staffid )>1)

实验二：模拟两个个字段数据重复

1.查询重复记录

方法一

select * from salary a

where (a.staffid,a.staff) in (select staffid,staff from salary group by staffid,staff having count(*) > 1)

方法二

SELECT *

FROM salary a

WHERE ((SELECT COUNT(*)

      FROM salary

      WHERE staffid = a.staffid and staff=a.staff) > 1)

ORDER BY staffid

结果，共15条

STAFFID

STAFF

1

 a

1

 a

1

 a

2

 s

2

 s

2

 s

3

 ert

3

 ert

3

 ert

4

 d

4

 d

4

 d

5

 b

5

 b

5

 b

2.删除重复数据，只保留1条，其余全部删除

delete from vitae a

where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)

and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)

3.查看删除后结果

select * from salary;

结果

STAFFID

STAFF

1

 oookkk

1

 a

2

 s

3

 ert

4

 d

5

 b

10

aaaa

20

sass

30

erwt

40

dsd

50

bsdf

来自 “ ITPUB博客 ” ，链接：http://blog.itpub.net/26964624/viewspace-2564339/