查询和删除数据表中反复数据的sql

1、查询表中反复数据。

select
* from people

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



2、删除表中多余的反复记录，反复记录是依据单个字段（peopleId）来推断。仅仅留有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、查找表中多余的反复记录（多个字段） 



elect * from vitae a

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



4、删除表中多余的反复记录（多个字段），仅仅留有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、查找表中多余的反复记录（多个字段）。不包括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)

例如说

在A表中存在一个字段“name”，

并且不同记录之间的“name”值有可能会同样，

如今就是须要查询出在该表中的各记录之间，“name”值存在反复的项；

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



假设还查性别也同样大则例如以下:

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



＂反复记录＂有两个意义上的反复记录，一是全然反复的记录，也即全部字段均反复的记录，二是部分keyword段反复的记录。比方Name字段反复，而其它字段不一定反复或都反复能够忽略。



　　1、对于第一种反复，比較easy解决。使用



select distinct * from tableName



　　就能够得到无反复记录的结果集。



　　假设该表须要删除反复的记录（反复记录保留1条）。能够按下面方法删除



select distinct * into #Tmp from tableName



drop table tableName



select * into tableName from #Tmp



drop table #Tmp



　　发生这样的反复的原因是表设计不周产生的，添加唯一索引列就可以解决。

　　2、这类反复问题通常要求保留反复记录中的第一条记录，操作方法例如以下



　　如果有反复的字段为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不反复的结果集（但多了一个autoID字段。实际写时能够写在select子句中省去此列）



(四)

查询反复



select * from tablename where id in (select id from tablename group by id 



having count(id) > 1）