Question

由于子查询返回行和列，因此您可以针对子查询加入，就像您可以加入普通表一样。

SELECT 
    P.ProductCode, I.QuantityInStock as Qty, P.Title, P.Price 
FROM 
    Products as P 
JOIN 
    (SELECT * FROM Inventory) as I on (P.ProductCode = I.ProductCode);

你怎么能重写这个查询，所以它不使用子查询？

我正在尝试重写但不确定是否正确

SELECT P.ProductCode, I.QuantityInStock as Qty, P.Title, P.Price
FROM Products as P
WHERE Inventory as I on (P.ProductCode = I.ProductCode);

这是对的吗？

Answer 1

SELECT P.ProductCode, I.QuantityInStock as Qty, P.Title, P.Price 
FROM   Products as P 
JOIN   Inventory as I on P.ProductCode = I.ProductCode;

Answer 2

由于您从库存中选择了所有列，您可以执行

SELECT 
    P.ProductCode, I.QuantityInStock as Qty, P.Title, P.Price 
FROM 
    Products as P 
JOIN 
    Inventory I on P.ProductCode = I.ProductCode;

Answer 3

SELECT P.ProductCode, I.QuantityInStock as Qty, P.Title, P.Price
FROM Products as P, Inventory as I
WHERE P.ProductCode = I.ProductCode

你怎么能重写这个查询不使用子查询？

3 个答案: