Question

表格如下：

Table: Shops

ShopCode   ShopName
--------   --------
A          Aladdin
B          Backstreet
C          Clerk's Store
D          Debs Tool

Table: Sale

ShopCode   Product
--------   -------
A          Hammer
A          Thermometer
A          Compass
B          Eraser
B          Hammer
C          Thermometer
C          Hammer
D          Thermometer

找到销售BOTH Hammer和Thermometer的商店的名称。结果表是

ShopName   
-------------- 
Aladdin
Clerk's Store

我认为以下查询可以正常工作，但是它返回空集

mysql> SELECT Shops.ShopName FROM Shops
    -> JOIN Sale ON Shops.ShopCode=Sale.ShopCode
    -> WHERE Sale.Product='Hammer' AND Sale.Product='Thermometer'
    -> GROUP BY Shops.ShopCode;

也尝试使用OR代替AND，但不能正常工作（返回所有商店）。什么是可能的解决方案？

为了使它有点清楚，我想选择同时具有两种物品（锤子和热水瓶）的商店，即使商店B销售锤子和D销售温度计，它们也不包括在内。只有销售这两件商品的A和C应该在结果上

Answer 1

有两个相当直接的选择。

您可以使用促销表加入两次，每件商品一次。如果您跳过DISTINCT，如果商店销售多个锤子或温度计，您可能会获得重复值。

SELECT DISTINCT s.shopname
FROM shops s
JOIN sale s1 ON s.shopcode = s1.shopcode AND s1.product='hammer'
JOIN sale s2 ON s.shopcode = s2.shopcode AND s2.product='thermometer';

...或者您可以找到锤子或温度计的所有匹配项，并计算有多少不同的值。如果有两个可能的值，并且两者都得到了，那就设置好了。

SELECT s.shopname
FROM shops s
JOIN sale s1 ON s.shopcode = s1.shopcode
WHERE s1.product IN('hammer','thermometer')
GROUP BY s.shopname
HAVING COUNT(DISTINCT s1.product)=2;

An SQLfiddle to test both

Answer 2

您可以轻松地在Sale表上加入两次 - 一次用于锤子，一次用于温度计，以便与两个锤子和Theremoeteres一起获得商店

 SELECT s.ShopName FROM Shops s  
      JOIN Sale s1 ON s.ShopCode=s1.ShopCode AND s1.Product='Thermometer'
      JOIN Sale s2 ON s1.ShopCode=s2.ShopCode AND s2.Product='Hammer'
  GROUP BY s.ShopName

Answer 3

我认为正确的Sql看起来像这样：

mysql> SELECT Shops.ShopName FROM Shops
    -> JOIN Sale ON Shops.ShopCode=Sale.ShopCode
    -> WHERE Sale.Product='Hammer' AND Sale.Product 'Thermometer'
    -> GROUP BY Shops.ShopCode;

OR

mysql> SELECT Shops.ShopName FROM Shops
    -> JOIN Sale ON Shops.ShopCode=Sale.ShopCode
    -> WHERE Sale.Product IN ('Hammer', 'Thermometer')
    -> GROUP BY Shops.ShopCode;

MySQL选择This和That

3 个答案: