如何从2个表中获得总价（数量和价格）

Question

我有2张桌子。我需要得到这两种产品的总成本，但我不能。问题是：购物中牛奶和奶酪的总成本是多少？

表：购物

Product | Quantity
–-----------------
Dogfood | 1
Milk    | 2
Soup    | 5
Cheese  | 1

表：产品

Product | Price
–--------------
Fish      123
Soup      657
Dogfood   210
Eggs      230
Cheese    120
Rhubarb   255
Milk      135
Banana    200
Apples    290
Lettuce    10

我在终端上使用此查询来获取MILK和CHEESE的总价，但是当我运行它时，它不会返回任何内容。

sqlite> SELECT Quantity*Price
...> FROM products INNER JOIN shopping
...> ON products.Product = shopping.Product
...> WHERE (products.Product = 'Cheese')AND (products.Product='Milk');

Answer 1

更新AND至OR，SUM(Quantity*Price)

SELECT SUM(Quantity*Price)
FROM products INNER JOIN shopping
ON products.Product = shopping.Product
WHERE (products.Product = 'Cheese') OR (products.Product='Milk');

Answer 2

SELECT Quantity*Price
FROM products INNER JOIN shopping
ON products.Product = shopping.Product
WHERE (products.Product = 'Cheese') **OR** (products.Product='Milk');

你试过这个吗？