Question

假设在数据库中的关联中有一个表：

Customer(Id, Name, City),

Orders(Cust_Id, Prod_Id),

Product(Id, Name, Price, Country)

理所当然Customer只订购了一次特定Product，我想执行以下查询：

1）获取来自Customers＆＃34; XY＆＃34; Products的{{1}}有序全部。

这是解决方案吗？：

Country

2）从Select * from Customers c join Orders o on c.id = o.orders.cust_id join Product p on o.prod_id = p.id where p.id = (Select id from Product where Product.country = "XY")＆＃34; XY＆＃34;

获取Customers订购的Products

两种情况下的正确查询是什么？

Answer 1

1）订购特定国家/地区的所有产品的客户：

DECLARE @Country AS VARCHAR(100)
SET @Country = 'XY'
;WITH OrdersCTE AS
(
    SELECT *
    FROM   Orders
    WHERE  Prod_Id IN (SELECT Id FROM Product WHERE Country = @Country)
)
SELECT * 
FROM   Customers
WHERE  Id IN 
(
    SELECT Cust_Id 
    FROM   OrdersCTE
    GROUP BY Cust_Id 
    HAVING COUNT(DISTINCT Prod_Id) = (SELECT COUNT(*) FROM Product WHERE Country = @Country)
)

2）仅购买特定国家/地区的产品的客户：

DECLARE @Country AS VARCHAR(100)
SET @Country = 'XY'
SELECT   C.Id,
         C.Name,
         C.City
FROM     Customers C
         Left JOIN Orders O
             ON C.Id = O.Cust_Id
         LEFT JOIN Product P
             ON P.Id = O.Prod_Id
GROUP BY C.Id,
         C.Name,
         C.City
HAVING   COUNT(DISTINCT Country) = 1

（高级）数据库关联表上的SQL查询

1 个答案: