oracle中如何刪除重數據

今天就跟大家聊聊有關oracle中如何刪除重數據，可能很多人都不太了解，為了讓大家更加了解，小編給大家總結了以下內容，希望大家根據這篇文章可以有所收獲。

前期準備

創建測試表

create table salary( 

  staffid   int, 

  staff   varchar(15)  

);

模擬重復數據

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');

實驗一：模擬單個字段數據重復

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.查出重復數據

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)

刪除重復數據，只保留1條，其余全部刪除

方法一，通過rowid刪除

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)

實驗二：模擬兩個個字段數據重復

1.查詢重復記錄

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 

結果，共15條

STAFFIDSTAFF

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.刪除重復數據，只保留1條，其余全部刪除

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.查看刪除后結果

select * from salary;

結果

STAFFIDSTAFF

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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