Question

我能够在excel中对其进行计算，但是发现在SQLite中提出正确的逻辑具有挑战性。

到目前为止，我已经尝试过：

   SELECT ProductName, productID, OrderDate
     FROM Product
LEFT JOIN OrderDetails 
       ON Product.ProductId = OrderDetails.ProductId
LEFT JOIN Orders 
       ON Orders.OrderId = OrderDetails.OrderId
    WHERE OrderDate 
  BETWEEN '1996/10/01' AND '1997/01/01' and 
          ProductID IS NULL
 GROUP BY ProductName

有人可以帮忙吗？

Answer 1

在我看来，您可以简单地使用NOT EXISTS条件来过滤在给定日期间隔内没有Orders的客户，例如：

SELECT c.*
FROM Customers c
WHERE NOT EXISTS (
    SELECT 1
    FROM Orders o
    WHERE 
        o.CustomerID = c.CustomerID 
        AND o.OrderDate BETWEEN '1996/10/01' AND '1997/01/01'
)

这也可以结合使用LEFT JOIN和IS NULL条件来完成：

SELECT c.*
FROM Customers c
LEFT JOIN Orders o
    ON o.CustomerID = c.CustomerID 
    AND o.OrderDate BETWEEN '1996/10/01' AND '1997/01/01'
WHERE o.OrderID IS NULL

在W3School提琴中，两个查询均返回57条记录。

Answer 2

您可以使用查询的变体形式获取过去3个月内订购的所有不同产品：

SELECT DISTINCT Products.ProductID
FROM Products
INNER JOIN OrderDetails ON Products.ProductId = OrderDetails.ProductId
INNER JOIN Orders ON Orders.OrderId = OrderDetails.OrderId
WHERE Orders.OrderDate BETWEEN '1996/10/01' AND '1997/01/01'

现在，您可以使用上述查询来获取过去3个月内未订购的所有产品：

SELECT p.ProductID, p.ProductName
FROM Products p LEFT JOIN (
    SELECT DISTINCT Products.ProductID 
    FROM Products
    INNER JOIN OrderDetails ON Products.ProductId = OrderDetails.ProductId
    INNER JOIN Orders ON Orders.OrderId = OrderDetails.OrderId
    WHERE Orders.OrderDate BETWEEN '1996/10/01' AND '1997/01/01'
) t 
ON t.ProductID = p.ProductID
WHERE t.ProductID IS NULL

或：

SELECT ProductID, ProductName
FROM Products 
WHERE ProductID NOT IN (
    SELECT DISTINCT Products.ProductID
    FROM Products
    INNER JOIN OrderDetails ON Products.ProductId = OrderDetails.ProductId
    INNER JOIN Orders ON Orders.OrderId = OrderDetails.OrderId
    WHERE Orders.OrderDate BETWEEN '1996/10/01' AND '1997/01/01'
)

两个查询均返回19种产品：

ProductID   ProductName
4           Chef Anton's Cajun Seasoning
5           Chef Anton's Gumbo Mix
6           Grandma's Boysenberry Spread
7           Uncle Bob's Organic Dried Pears
8           Northwoods Cranberry Sauce
10          Ikura
15          Genen Shouyu
18          Carnarvon Tigers
20          Sir Rodney's Marmalade
24          Guaraná Fantástica
25          NuNuCa Nuß-Nougat-Creme
32          Mascarpone Fabioli
39          Chartreuse verte
43          Ipoh Coffee
45          Røgede sild
51          Manjimup Dried Apples
52          Filo Mix
58          Escargots de Bourgogne
67          Laughing Lumberjack Lager

使用EXCEPT也可以得到相同的结果：

SELECT p.ProductID, p.ProductName 
FROM Products p INNER JOIN (
    SELECT ProductID
    FROM Products 
    EXCEPT 
    SELECT DISTINCT Products.ProductID
    FROM Products
    INNER JOIN OrderDetails ON Products.ProductId = OrderDetails.ProductId
    INNER JOIN Orders ON Orders.OrderId = OrderDetails.OrderId
    WHERE Orders.OrderDate BETWEEN '1996/10/01' AND '1997/01/01'
) t ON t.ProductID = p.ProductID

SQLite查询联接逻辑

2 个答案: