SQL 合并表的问题！高手请进
Table 1

OutDate ItemNumber Qty1
2007/7/1 A00001 20
.
.
.
2007/7/31 A00001 30
(Table 1 中存放很多Itemnumber 在一个月内每一天的Qty1)

Table 2

OutDate ItemNumber Qty2
2007/7/5 A00001 21
2007/7/9 A00001 28
2007/7/14 A00901 14
...
(Table 2 中存放一些Itemnumber某月内的某些日期的Qty2)

Table C

OutDate Itemnumber Qty1 Qty2
2007/7/1 A00001 21 0
.
.
.
2007/7/5 A00001 0 21
.
.
.
2007/7/31 A00001 31 0
2007/7/1 A00901 0 14
2007/7/31 A00901 0 0
......




[解决办法]
try

Select
A.OutDate,
A.Itemnumber,
A.Qty1,
IsNull(B.Qty2, 0) As Qty2
From
Table1 A
Left Join
Table2 B
On A.OutDate = B.OutDate And A.Itemnumber = B.Itemnumber
[解决办法]
--try:
--或者用full join
select A.OutDate , A.ItemNumber , A.Qty1, isnull(B.Qty2,0) as Qty2
from Table1 A
left join Table2 B
on A.OutDate=B.OutDate and A.ItemNumber=B.ItemNumber
[解决办法]
(Table 1 中存放很多Itemnumber 在一个月内每一天的Qty1)

-------------
所以我得用Left Join就可以了