oracle怎么查询重复的数据

在oracle中，可以利用count()函数配合select查询语句来查询重复的数据，语法为“select userCode from user group by userCode having count(userCode)>1”。

本教程操作环境：Windows10系统、Oracle 11g版、Dell G3电脑。

oracle怎么查询重复的数据

1、查找表中多余的重复记录，重复记录是根据单个字段（userCode）来判断

select 
    * 
from 
    user
where 
    userCode
in 
    (select  userCode  from  user group by  userCode having count (userCode) > 1)

2、删除表中多余的重复记录，重复记录是根据单个字段（userCode）来判断，只留有rowid最小的记录

delete from 
    user 
where 
    userCode 
in 
    (select userCode from user group by  userCode having count (peopleId) > 1)
and rowid not in 
    (select min(rowid) from   user group by userCode having count(userCode)>1)

3、查找表中多余的重复记录（多个字段）

select 
    * 
from 
    user a
where 
    (a.userCode,a.userName) 
in  
    (select userCode,userName from user group by userCode,userName 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 
    user a
where
    (a.userCode,a.userName) 
in   
    (select userCode,userName from user group by userCode,userName having count(*) > 1)
and rowid not in 
    (select min(rowid) from user group by userCode,userName 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 
    user a
where 
    (a.userCode,a.userName)  
in   
    (select userCode,userName from user group by userCode,userName having count(*) > 1)
and rowid not in 
    (select min(rowid) from user group by userCode,userName having count(*)>1)

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