这个左外连接怎么做

[Tom_ruanbb]

2张视图
v1
ManufactureID ProductionID WID
1 1 1
1 1 2

V2
ManufactureID ProductionID WID Quantity
1 1 1 3

select isnull(Quantity,0) as 'num' from v1 left join v2
on v1.ManufactureID =v2.ManufactureID
and v1.ProductionID=v2.ProductionID
and v1.WID=v2.WID

预想结果：
num
1
0

可结果为：
num
1

这是为什么？？？？

[caixia615]

用all join
try

[marco08]

create table v1(ManufactureID int, ProductionID int, WID int)
insert v1 select 1, 1, 1
union all select 1, 1, 2

create table v2(ManufactureID int, ProductionID int, WID int, Quantity int)
insert v2 select 1, 1, 1, 3

select isnull(v2.Quantity,0) as 'num'
from v1
left join v2
on v1.ManufactureID =v2.ManufactureID
and v1.ProductionID=v2.ProductionID
and v1.WID=v2.WID

--result
num
-----------
3
0

(2 row(s) affected)

[caixia615]

用left join可以的不过结果应该是
3
0

[dongrenyi]

对啊，应该不会是
1
0
啊