连续两个where

[linguojin11]

今天在看一帖子时看到乌龟这样写：
create table tb(name varchar(10) , sex varchar(10) , age int)
insert into tb values('A' , 'M' , 17 )
insert into tb values('B' , 'M' , 22 )
insert into tb values('A' , 'F' , 67 )
insert into tb values('A' , 'M' , 17 )
go
select m.* from tb m
where exists (select 1 from ( select name , sex from tb group by name , sex having count(*) > 1 ) n
where n.name = m.name and n.sex = m.sex
)
请问下大家这是什么格式，为什么可以连续两个where..

[csdyyr]

子查询

[bennyyyyy]

不同查询语句的条件

[水族杰纶]

子查询

[oraclelogan]

[Quote=引用楼主 linguojin11 的帖子:]
今天在看一帖子时看到乌龟这样写：
[/Quote]

兄弟，这是条件子查询啊，where里面套用where啊！
create table tb(name varchar(10) , sex varchar(10) , age int) 
insert into tb values('A' ,    'M' ,  17 ) 
insert into tb values('B' ,    'M' ,  22 ) 
insert into tb values('A' ,    'F' ,  67 ) 
insert into tb values('A' ,    'M' ,  17 ) 
go 
select m.* from tb m 
where exists (
	select 1 from ( select name , sex  from  tb group by name , sex  having count(*) > 1 ) n 
	where n.name = m.name and n.sex = m.sex 
) 

[oraclelogan]

[Quote=引用楼主 linguojin11 的帖子:]
今天在看一帖子时看到乌龟这样写：
create table tb(name varchar(10) , sex varchar(10) , age int)
insert into tb values('A' , 'M' , 17 )
insert into tb values('B' , 'M' , 22 )
insert into tb values('A' , 'F' , 67 )
insert into tb values('A' , 'M' , 17 )
go
select m.* from tb m
where exists (select 1 from ( select name , sex from tb group by name , sex having count…
[/Quote]

现在明白了没有，楼主！？

[oflying907]

select m.* from tb m
where 
	exists (select 1 
			from ( select name , sex  from  tb group by name , sex  having count(*) > 1 ) n
			where n.name = m.name and n.sex = m.sex
) 

[linguojin11]

呵呵。。不好意思，刚才看晕了，把where给看成并列语句了，所以就纳闷。。。谢谢。。大家速度太快了