Question

我有这两个表：

Cart_Details（Cart_ID，Product_ID，Quantity，Subtotal）
产品（Product_ID，名称，描述）

我的SQL声明：

SELECT TOP 5 
    t1.Product_ID, 
    t1.Name,
    t1.Category,
    (SELECT COUNT(*) 
     FROM Cart_Details
     WHERE Cart_Details.Product_ID = t1.Product_ID) AmountSold,
    (SELECT Quantity 
     FROM Cart_Details 
     WHERE t1.Product_ID = Cart_Details.Product_ID) AS Quantity,
    (Quantity * AmountSold) AS FinalSold
FROM 
    [dbo].[Product] t1

我正在尝试将别名（AmountSold和Quantity）的值乘以并将结果设为FinalSold，但我收到错误：

无效的列名称'AmountSold'。

和

无效的列名称'Quantity'。

我是否有其他方法可以将两个别名的值添加到新列中？

Answer 1

使用计算字段的一种方法是将其包装在子查询中：

SELECT 
    *,
    (Quantity*AmountSold)AS FinalSold
FROM (SELECT top 5 
         t1.Product_ID, 
         t1.Name,
         t1.Category,
         (select count(*) 
          from Cart_Details
          where Cart_Details.Product_ID=t1.Product_ID ) AmountSold,
         (select Quantity 
          from Cart_Details 
          where t1.Product_ID=Cart_Details.Product_ID) AS Quantity,
    FROM [dbo].[Product] t1) AS InnerTable

Answer 2

另一种方法是使用CTE：

;WITH CTEQuery AS 
 (SELECT  
         t1.Product_ID, 
         t1.Name,
         t1.Category,
        (select count(*) 
         from   Cart_Details
         where  Cart_Details.Product_ID = t1.Product_ID) AmountSold,
        (select Quantity 
         from   Cart_Details 
         where  t1.Product_ID=Cart_Details.Product_ID) AS Quantity             
   FROM [dbo].[Product] t1)

SELECT  top 5 (Quantity*AmountSold) AS FinalSold, *
FROM    CTEQuery

乘法别名时列名无效

2 个答案: