Question

尝试查询此消息时，我有些卡住：查找订购了与客户编号250相同的所有客户

数据库架构：

Customers(
customerNumber INTEGER, PRIMARY KEY
);

Orders(
orderNumber INTEGER, PRIMARY KEY
customerNumber INTEGER NOT NULL,
FOREIGN KEY (customerNumber) REFERENCES Customers
);

OrderDetails (
  orderNumber INTEGER NOT NULL,
  productCode TEXT NOT NULL,
  PRIMARY KEY (orderNumber, productCode),
  FOREIGN KEY (productCode) REFERENCES Products
);

我想到了这个查询：

select DISTINCT customerNumber
  FROM Orders Natural 
  JOIN OrderDetails
 WHERE productCode NOT IN (
    select productCode
    FROM Orders NATURAL JOIN OrderDetails
    WHERE customerNumber = 219
)    
order by customerNumber;

将是正确的，但是它什么也不会返回，所以很明显我误会了一些东西。

Answer 1

当您需要所有客户时，都订购了250个订单或250个以上但具有相同产品的所有产品，因此请尝试使用条件汇总

   select customerNumber
      FROM Orders o
      JOIN OrderDetails od 
     on o.orderNumber =od.orderNumber 
     WHERE od.productCode IN (
        select productCode
        FROM Orders o
       JOIN OrderDetails od 
       on o.orderNumber =od.orderNumber
        WHERE customerNumber = 250
    )    
     group by customerNumber
    having count(distinct productCode )>= 
        (select count(distinct productCode )
        FROM Orders o
       JOIN OrderDetails od 
       on o.orderNumber =od.orderNumber
        WHERE customerNumber = 250)

多个行匹配的SQLite查询测试

1 个答案: