菜鸟求一个不算太难的SQL语句。

[hanyangjian]

A表
id title
1 生活
2 娱乐
3 旅游

B表
id URL Aid
1 地址1 1
2 地址2 1
3 地址3 1
4 地址4 2
5 地址5 2



需要结果
aid tile url
1 生活 地址3
2 娱乐 地址5
3 旅游 null

[bancxc]

select A.*,url from A left join B where A.id=B.Aid

[bancxc]

select A.*,url from A left join B on A.id=B.Aid

[dawugui]

select a.* , t.url
from a left join b t
on a.id = t.aid and t.id = (select max(id) from b where aid = t.aid)

[bancxc]

select A.*,url=(select top 1 url from b where b.aid=a.id order by id desc) from A

[dawugui]

create table A(id int, title varchar(10))
insert into a values(1 , '生活') 
insert into a values(2 , '娱乐') 
insert into a values(3 , '旅游') 
create table B(id int, URL varchar(10),   Aid int)
insert into b values(1 , '地址1' ,   1 )
insert into b values(2 , '地址2' ,   1 )
insert into b values(3 , '地址3' ,   1 )
insert into b values(4 , '地址4' ,   2 )
insert into b values(5 , '地址5' ,   2 )
go

select a.* , t.url 
from a left join b t 
on a.id = t.aid and t.id = (select max(id) from b where aid = t.aid)

select a.* , t.url 
from a left join b t 
on a.id = t.aid and not exists (select 1 from b where aid = t.aid and id > t.id)

drop table a , b

/*
id          title      url        
----------- ---------- ---------- 
1           生活         地址3
2           娱乐         地址5
3           旅游         NULL

（所影响的行数为 3 行）

id          title      url        
----------- ---------- ---------- 
1           生活         地址3
2           娱乐         地址5
3           旅游         NULL

（所影响的行数为 3 行）

*/

[--小F--]

select
 a.* , t.url 
from
 a left join b t 
on
 a.id = t.aid 
and
 t.id = (select max(id) from b where aid = t.aid)

[chinesesword]

select aid ,tile, MAX(url) from
A left join B where A.id=B.Aid
group by aid ,tile

[叶子]

declare @A表 table (id int,title varchar(4))
insert into @A表
select 1,'生活' union all
select 2,'娱乐' union all
select 3,'旅游'

declare @B表 table (id int,URL varchar(5),Aid int)
insert into @B表
select 1,'地址1',1 union all
select 2,'地址2',1 union all
select 3,'地址3',1 union all
select 4,'地址4',2 union all
select 5,'地址5',2

select  a.* ,
        b.url
from    @A表 a
        left join ( select  Aid ,
                            max(URL) as url
                    from    @B表
                    group by Aid
                  ) b on a.id = b.Aid

/*
id          title url
----------- ----- -----
1           生活    地址3
2           娱乐    地址5
3           旅游    NULL
*/

[jiyan1221]

LZ第一列是aid ？如果是aid，给的题目好像有问题啊

[心中的彩虹]

--表结构及记录
if object_id('A') is not null drop table A
create table A(id int, title varchar(10))
insert into a values(1 , '生活')
insert into a values(2 , '娱乐')
insert into a values(3 , '旅游')
if object_id('B') is not null drop table B
create table B(id int, URL varchar(10), Aid int)
insert into b values(1 , '地址1' , 1 )
insert into b values(2 , '地址2' , 1 )
insert into b values(3 , '地址3' , 1 )
insert into b values(4 , '地址4' , 2 )
insert into b values(5 , '地址5' , 2 )
--语句
select A.id as aid,title,max(URL)
from A left join B on A.id=b.aid
group by a.id,title