如何在選擇的另一列上使用最大功能

Question

有詢問是詢問每個客戶購買的最喜歡的產品。我必須選擇，並在第一選擇我已經選擇了每個客戶購買的產品數量。在另一個選擇中，我想爲每個客戶選擇最大的boughts。但是當我想選擇max（先前的選擇列）時，它會得到並顯示錯誤，並說它沒有定義，任何人都可以幫助我解決這個問題。我非常願意從這種方式解決問題，我不願意使用其他方法創建視圖或類似的東西。任何一個可以幫助我在此：

SELECT INN.Maximum,INN.Name, customer.ProductName from 
(SELECT ContactName, ProductName, COUNT([Order Details].Quantity) AS NumOftimeCustomer 
FROM Orders, [Order Details], Products, Customers 
WHERE [Order Details].OrderID = Orders.OrderID 
AND [Order Details].ProductID = Products.ProductID 
AND Orders.CustomerID = Customers.CustomerID 
GROUP BY ContactName, ProductName)customer 
INNER JOIN 
(SELECT Customers.ContactName AS Name, **MAX(customer.numOftimecustomer)** AS Maximum 
from Customers, customer 
GROUP BY Customers.ContactName) INN 
ON INN.Name = customer.ContactName AND INN.Maximum = customer.NumOftimeCustomer 

這與MAX（customer.numOftimecustomer） **提到，部分是給出了錯誤的部分，它說的對象客戶是沒有定義。有沒有辦法解決它沒有看法？爲什麼這樣呢？因爲我定義的客戶不是桌子？

Answer 1

這裏是你想要的東西：

select 
    * 
from (SELECT ContactName, ProductName, COUNT([Order Details].Quantity) AS NumOftimeCustomer 
    FROM Orders, [Order Details], Products, Customers 
    WHERE [Order Details].OrderID = Orders.OrderID 
    AND [Order Details].ProductID = Products.ProductID 
    AND Orders.CustomerID = Customers.CustomerID 
    GROUP BY ContactName, ProductName)customer 
where customer.num = (select max(num) from 

(SELECT ContactName, ProductName, COUNT([Order Details].Quantity) AS NumOftimeCustomer 
    FROM Orders, [Order Details], Products, Customers 
    WHERE [Order Details].OrderID = Orders.OrderID 
    AND [Order Details].ProductID = Products.ProductID 
    AND Orders.CustomerID = Customers.CustomerID 
    GROUP BY ContactName, ProductName)customer2 
where customer2.name = customer.name)