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oracle删除重数据方法

原创 Oracle 作者:巡完南山巡南山 时间:2019-01-21 21:28:22 0 删除 编辑

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

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