删除数据库重复记录sql语句分享__peopleId_select_from_rowid_having_

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删除数据库重复记录sql语句分享

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本文导语: 在使用sql数据库时，经常会遇到如何删除数据库中重复记录的问题？这里分大家分享几种删除重复记录的方法，一些常用的sql语句，一起来看看吧。 1、查找表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断 ...

在使用sql数据库时，经常会遇到如何删除数据库中重复记录的问题？

这里分大家分享几种删除重复记录的方法，一些常用的sql语句，一起来看看吧。

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

代码示例:

select * from people

where peopleId in (select  peopleId  from  people  group  by  peopleId  having  count(peopleId) > 1)

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

代码示例:

delete from people 

where peopleId  in (select  peopleId  from people  group  by  peopleId   having  count(peopleId) > 1)

and rowid not in (select min(rowid) from  people  group by peopleId  having count(peopleId )>1)

3、查找表中多余的重复记录（多个字段）

代码示例:

select * from vitae a

where (a.peopleId,a.seq) in  (select peopleId,seq from vitae group by peopleId,seq  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

代码示例:

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)

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

代码示例:

select * 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)

相关阅读：

sql server中distinct筛选重复记录的用法举例
sql server 查询重复记录的多种方法
sql server 重复记录的取最新一笔的实现方法

sql查询重复记录、删除重复记录方法大全（sql语句大全）

查找所有重复标题的记录：

代码示例:

SELECT *

FROM t_info a

WHERE ((SELECT COUNT(*)

FROM t_info

WHERE Title = a.Title) > 1)

ORDER BY Title DESC

一、查找重复记录

1，查找全部重复记录

代码示例:

Select * From 表 Where 重复字段 In (Select 重复字段 From 表 Group By 重复字段 Having Count(*)>1)

2，过滤重复记录(只显示一条)

代码示例:

Select * From HZT Where ID In (Select Max(ID) From HZT Group By Title)

注：此处显示ID最大一条记录

二、删除重复记录

1、删除全部重复记录（慎用）

代码示例:

Delete 表 Where 重复字段 In (Select 重复字段 From 表 Group By 重复字段 Having Count(*)>1)

2、保留一条

代码示例:

Delete HZT Where ID Not In (Select Max(ID) From HZT Group By Title)

注：此处保留ID最大一条记录。

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

代码示例:

select * from people

where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)

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

代码示例:

delete from people 

where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)

and rowid not in (select min(rowid) from people group by peopleId having count(peopleId )>1)

3、查找表中多余的重复记录（多个字段）

代码示例:

select * from vitae a

where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq 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

代码示例:

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)

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

代码示例:

select * 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)

补充：
有两个以上的重复记录，一是完全重复的记录，也即所有字段均重复的记录，二是部分关键字段重复的记录，比如Name字段重复，而其他字段不一定重复或都重复可以忽略。

1、对于第一种重复，比较容易解决，使用

代码示例:

select distinct * from tableName

就可以得到无重复记录的结果集。

如果该表需要删除重复的记录（重复记录保留1条），可以按以下方法删除

代码示例:

select distinct * into #Tmp from tableName

drop table tableName

select * into tableName from #Tmp

drop table #Tmp

发生这种重复的原因是表设计不周产生的，增加唯一索引列即可解决。

2、这类重复问题通常要求保留重复记录中的第一条记录，操作方法如下
假设有重复的字段为Name,Address，要求得到这两个字段唯一的结果集

代码示例:

select identity(int,1,1) as autoID, * into #Tmp from tableName

select min(autoID) as autoID into #Tmp2 from #Tmp group by Name,autoID

select * from #Tmp where autoID in(select autoID from #tmp2)