sql 中的查询表达式中的语法错误（缺少运算符）

Question

我是 SQL 的首发。 我正在使用来自 w3schools 的 SQL Tryit Editor v1.6，但我遇到了一个错误

“查询表达式ORD.OrderID = FREQ.OrderID INNER JOIN Customers AS CUS ON CUS.CustomerID = ORD.CustomerID中的语法错误（缺少运算符）。”

（这正是我得到的错误）

但我真的不知道如何解决它。

这是我的代码：

SELECT
    ProductID,
    COUNT(ProductID)
FROM 
    OrderDetails AS FREQ 
INNER JOIN 
    Orders AS ORD ON ORD.OrderID = FREQ.OrderID
INNER JOIN 
    Customers AS CUS ON CUS.CustomerID = ORD.CustomerID 
WHERE 
    Country = 'Germany'
GROUP BY 
    ProductID 
ORDER BY 
    COUNT(ProductID) DESC

Answer 1

请试试这个：

SELECT
FREQ.ProductID,
COUNT(FREQ.ProductID)
FROM OrderDetails AS FREQ 
INNER JOIN Orders AS ORD 
ON ORD.OrderID = FREQ.OrderID
INNER JOIN Customers AS CUS 
ON CUS.CustomerID = ORD.CustomerID 
WHERE Country = 'Germany'
GROUP BY FREQ.ProductID 
ORDER BY COUNT(FREQ.ProductID) DESC