SQL重复记录查询的几种方法

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

复制代码 代码如下:

select * from people
where peopleId in (select peopleId from people group by peopleId having count

(peopleId) > 1)

复制代码 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)

复制代码 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)

复制代码 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)

复制代码 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)

复制代码 代码如下:

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

复制代码 代码如下:

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

复制代码 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

　　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

复制代码 代码如下:

select distinct * from tableName

　　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

复制代码 代码如下:

select distinct * into #Tmp from tableName
drop table tableName
select * into tableName from #Tmp
drop table #Tmp

　　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

复制代码 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)

在select子句中省去此列）

(四)查询重复

复制代码 代码如下:

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