Sql 无效的列名'；最终总额'；

这是我的代码，它一直在说无效的列名“FinalTotal”。我做错了什么？

不能在同一查询中引用派生值

试一试

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不能在同一查询级别上使用这样的列别名

在计算ItemTotal时使用FinalToal的完整表达式

SELECT o.OrderID
, ProductName
, OrderDate
, ItemPrice
, TaxAmount
, DiscountAmount
,DiscountAmount - ItemPrice AS FinalTotal
, Quantity
, ShipDate
,(DiscountAmount - ItemPrice) * Quantity AS ItemTotal
FROM Orders AS o JOIN OrderItems AS oi
    ON o.OrderID = oi.OrderID
 JOIN Products AS p
    ON oi.ProductID = p.ProductID;

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或者简单地使用派生查询或CTE，因为表中没有名为FinalTotal的列，这是一个计算列

请使用以下选项

SELECT o.OrderID, ProductName, OrderDate, ItemPrice, TaxAmount, DiscountAmount,
       DiscountAmount - ItemPrice AS FinalTotal, 
       Quantity, ShipDate,
       (DiscountAmount - ItemPrice) * Quantity AS ItemTotal
FROM Orders AS o JOIN OrderItems AS oi
    ON o.OrderID = oi.OrderID
 JOIN Products AS p
    ON oi.ProductID = p.ProductID;

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在SQL Server中执行此操作的一个技巧是使用

apply

：

        SELECT o.OrderID, ProductName, OrderDate, ItemPrice, TaxAmount, DiscountAmount,
       DiscountAmount - ItemPrice AS FinalTotal, 
       Quantity, ShipDate,
       (DiscountAmount - ItemPrice) * Quantity AS ItemTotal
FROM Orders AS o JOIN OrderItems AS oi
    ON o.OrderID = oi.OrderID
 JOIN Products AS p ON oi.ProductID = p.ProductID;

---

FinalTotal*数量

->

（折扣金额-项目价格）*数量

谢谢，我现在就试试。

        SELECT o.OrderID, ProductName, OrderDate, ItemPrice, TaxAmount, DiscountAmount,
       DiscountAmount - ItemPrice AS FinalTotal, 
       Quantity, ShipDate,
       (DiscountAmount - ItemPrice) * Quantity AS ItemTotal
FROM Orders AS o JOIN OrderItems AS oi
    ON o.OrderID = oi.OrderID
 JOIN Products AS p ON oi.ProductID = p.ProductID;

SELECT o.OrderID, ProductName, OrderDate, ItemPrice, TaxAmount, 
       DiscountAmount, x.FinalTotal, Quantity, ShipDate,
       x.FinalTotal * Quantity AS ItemTotal
FROM Orders o JOIN
     OrderItems AS oi
     ON o.OrderID = oi.OrderID JOIN
     Products AS p
     ON oi.ProductID = p.ProductID CROSS APPLY
     (SELECT (DiscountAmount - ItemPrice) as FinalTotal) x