SQL重复记录查询的几种方法(转)

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

代码如下:

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

代码如下:

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） 

代码如下:

select * from vitae a
where (a.peopleId,a.seq) in   (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)

上面的语句会出现错误：

消息 102，级别 15，状态 1，第 2 行
',' 附近有语法错误。
消息 156，级别 15，状态 1，第 3 行
关键字 'and' 附近有语法错误。

改成如下

select * from dbo.Organization a
where a.ORG_CODEA in  (select ORG_CODEA from Organization group by ORG_CODEA,ORG_CLASS having count(*) > 1)
and a.ORG_CLASS in  (select ORG_CLASS from Organization group by ORG_CODEA,ORG_CLASS having count(*) > 1)
and ORG_ID not in (select min(ORG_ID) from Organization group by ORG_CODEA,ORG_CLASS having count(*)>1)--不包含ORG_ID最小的记录

或

select *  from dbo.Organization a
where exists (select 1 from (select ORG_CODEA,ORG_CLASS from Organization group by ORG_CODEA,ORG_CLASS having count(*) > 1) s
         where s.ORG_CODEA = a.ORG_CODEA
           and s.ORG_CLASS = a.ORG_CLASS)

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

代码如下:

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

代码如下:

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；

代码如下:

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

如果还查性别也相同大则如下:

代码如下:

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

(三)

方法一

 代码如下:

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

代码如下:

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

代码如下:

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

代码如下:

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

代码如下:

select * from tablename where id in (
select id from tablename
group by id
having count(id) > 1
)

 

select * from dbo.Organization a
where (a.ORG_CODEA+a.ORG_CLASS) in  (select ORG_CODEA+ORG_CLASS from Organization group by ORG_CODEA,ORG_CLASS having count(*) > 1)
and ORG_ID not in (select min(ORG_ID) from Organization group by ORG_CODEA,ORG_CLASS having count(*)>1)



select ORG_CODEA,ORG_CLASS
from Organization
group by ORG_CODEA,ORG_CLASS
having count(*)>1