根据sql中另一个表的组合求和

Question

我有两张桌子：

表1有销售的项目

+-------+-------+
| Items | Sales |
+-------+-------+
| A     | 34    |
+-------+-------+
| B     | 22    |
+-------+-------+
| C     | 10    |
+-------+-------+

表2

组合

+-------+-------+
| item1 | item2 |
+-------+-------+
| A     | B     |
+-------+-------+
| C     | B     |
+-------+-------+
| C     | A     |
+-------+-------+

我想要从表1中组合Item1和item2值的总和，例如A + B.

Answer 1

将组合表与Item表连接两次

select b.sales+c.sales as totalval from combination a
inner join item b on a.item1=b.Items
inner join item c on a.item2=c.Items

Answer 2

请试试这个。

SELECT(A.Sales + B.Sales) AS Total, * FROM Combination
INNER JOIN ITEM A ON A.Items = C.Item1
INNER JOIN ITEM  B ON  B.Items = C.Item2