sql查询问题

[fengzairenjian]

用SQL做查询，两个表，ID关联，A表很全，B表有的没有，怎么让B表没有的都显示为0？
比如A表：ID：001，002，003
B表ID：002，
AMOUNT：100

我想查出这样的效果
ID AMOUNT
001 0
002 100
003 0


用SQL怎么写？

[playwarcraft]

select A.id,isnull(B.amount,0) as amount
from A
left join B
on A.id=B.id

[chuifengde]

select a.id,isnull(amount,0) amount from a left join b on a.id=b.id

[威尔亨特]

左链接，和右表没有匹配的数据也出

[fa_ge]

select a.id,isnull(amount,0) amount from a left join b on a.id=b.id

[areswang]

isnull()

[wanglei8]

create table A(ID int)
insert A select 001 union all select 002 union all select 003
create table B(ID int,AMOUNT int)
insert B select 002,100


select A.ID , isnull(B.AMOUNT,0) as AMOUNT from A left join B on A.ID=B.ID