SQL SELECT從兩個

Question

TABLE1

ID |  DATE 
a | 10-06-2012 | 
b | 07-07-2012 | 
c | 10-06-2012 | 

TABLE2

ID | COST | 
a | 3 | 
b | 4 | 
c | 4 | 

我有兩個表，我想搜索的DATE例如10-06-2012並且返回總計COST對於那個DATE是7.

ID在兩個表中都是通用的。

Answer 1

連接表，並使用sum骨料添加值：

select sum(t2.COST) 
from TABLE1 as t1 
inner join TABLE2 as t2 on t2.ID = t1.ID 
where t1.DATE = '10-06-2012'