SQL重复记录查询

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 

select * from people
where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)
例二: 

select * from testtable
where numeber in (select number from people group by number having count(number) > 1 )
可以查出testtable表中number相同的记录  
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 

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)  

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 

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 

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)

(二) 

比方说 

在A表中存在一个字段“name”, 

而且不同记录之间的“name”值有可能会相同, 

现在就是需要查询出在该表中的各记录之间,“name”值存在重复的项; 

Select Name,Count(*) From A Group By Name Having Count(*) > 1
如果还查性别也相同大则如下: 

Select Name,sex,Count(*) From A Group By Name,sex Having Count(*) > 1

(三) 

方法一 

declare @max integer,@id integer

declare cur_rows cursor local for select 主字段,count(*) from 表名 group by 主字段 having count(*) >; 1

open cur_rows

fetch cur_rows into @id,@max

while @@fetch_status=0

begin

select @max = @max -1

set rowcount @max

delete from 表名 where 主字段 = @id

fetch cur_rows into @id,@max

end

close cur_rows

set rowcount 0
方法二  
有两个意义上的重复记录,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 

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 

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 

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)
最后一个select即得到了Name,Address不重复的结果集(但多了一个autoID字段,实际写时可以写在select子句中省去此列)  
(四)  
查询重复 

select * from tablename where id in (

select id from tablename

group by id

having count(id) > 1

)

以上就是小编为大家带来的SQL重复记录查询 查询多个字段、多表查询、删除重复记录的方法的全部内容了,希望对大家有所帮助,多多支持脚本之家~

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