如何在同一个数据库表中查询出相同的记录

[ddzdlz010]

如何在同一个数据库表中查询出相同的记录，并删除相同的记录：

例如：bh xm
0001 王明
0001 王明
0002 张华
0003 王平
0003 王平

显示结果：
bh xm
0001 王明
0002 张华
0003 王平

[wzy_love_sly]

用临时表

[wzy_love_sly]

create table tb(bh varchar(20),xm varchar(10))
insert into tb select '0001','王明'
insert into tb select '0001','王明'
insert into tb select '0002','张华'
insert into tb select '0003','王平'
insert into tb select '0003','王平'

select * into # from (select distinct * from tb)tp
delete tb
insert into tb select * from #
select * from tb

bh xm
0001 王明
0002 张华
0003 王平

[dawugui]

如果bh+xm 存在重复,则sql server 2000只能使用临时表来解决.

[dawugui]

详细说明如下:
--如何按字段删除重复记录

一张表里面以两个字段为唯一字段，当几条记录的这两个字段完全相同时，需要删除重复项，如下表
a b c d
1 2 3 4
1 5 3 5
1 2 7 9
以a、b为唯一字段，第一条和第三条的a、b完全相同，所以，需要删除第一条记录1 2 3 4 或者第三条记录1 2 7 9
即如下结果：
a b c d
1 2 3 4
1 5 3 5
或
a b c d
1 5 3 5
1 2 7 9

请问各位大侠这种sql语句怎么写


CREATE TABLE Tb1(id int, [a] varchar(255), [b] varchar(255), [c] varchar(255), [d] varchar(255))
INSERT Tb1(id, [a], [b], [c], [d])
SELECT 1, '1','2','3','4'
UNION ALL SELECT 2, '1','5','3','5'
UNION ALL SELECT 3, '1','2','7','9'
UNION ALL SELECT 4, '1','4','7','6'

delete Tb1 where [id] not in (select max([id]) from Tb1 group by a,b )
select * from tb1

drop table tb1

如果要同时删除第一和第三行
即如下结果：
a b c d
1 5 3 5

语句如下：

delete m from tb t
inner join
(
select a ,b
from tb
group by a , b
having count(*)>1
)n
on m.a = n.a and m.b = n.b
或
delete * from tb as m,
(
select a ,b
from tb
group by a , b
having count(*)>1
)n
where m.a = n.a and m.b = n.b








------------------------------------------------------------------------------------
在几千条记录里,存在着些相同的记录,如何能用SQL语句,删除掉重复的呢?谢谢!
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)

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)

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

[-狙击手-]

select distinct * from tb

[nextflying]

临时表抽取 ， 然后删除 插入之

[love398146779]

oracle中应用不出一点问题。sqlserver不敢保证
delete from T_UEC_USER a
where a.xm in (select xm from T_UEC_USER group by xm having count(*) > 1)
and rowid not in (select min(rowid) from T_UEC_USER group by xm having count(*)>1)

[love398146779]

假定表名为 T_UEC_USER，忘说了。

[love398146779]

delete from T_UEC_USER a
where (a.bh,a.xm) in (select bh,xm from T_UEC_USER group by bh,xm having count(*)>1)
and rowid not in (select min(rowid) from T_UEC_USER group by bh,xm having count(*)>1)

[feifa_2002]

路过，学习

[siegebaoniu]

[Quote=引用 4 楼 dawugui 的回复:]
详细说明如下:
--如何按字段删除重复记录

一张表里面以两个字段为唯一字段，当几条记录的这两个字段完全相同时，需要删除重复项，如下表
a b c d
1 2 3 4
1 5 3 5
1 2 7 9
以a、b为唯一字段，第一条和第三条的a、b完全相同，所以，需要删除第一条记录1 2 3 4 或者第三条记录1 2 7 9
即如下结果：
a b c d
1 2 3 4
1 5 ……
[/Quote]

太牛叉了！