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)
查询重复

select
* from tablename
where id
in (

select id
from tablename

group
by id

having
count(id)
> 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)










































































































