C# SQL查询不能使用别名，但可以使用索引

上面的代码有效，但下面的代码无效，并返回此错误

SELECT        Product_ID, Product_Name, Purchase_Cost, Quantity_On_Hand, Purchase_Cost*Quantity_On_Hand AS Total_Item_Value
FROM            PRODUCT
ORDER BY 5 DESC

错误：

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MS Access基本上不允许在查询中的任何位置重用别名。您可以使用列号（与以前一样）、重复表达式或使用子查询：

SELECT        Product_ID, Product_Name, Purchase_Cost, Quantity_On_Hand, Purchase_Cost*Quantity_On_Hand AS Total_Item_Value
FROM            PRODUCT
ORDER BY Total_Item_Value DESC

或：

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这回答了你的问题吗？

SELECT Product_ID, Product_Name, Purchase_Cost, Quantity_On_Hand, Purchase_Cost * Quantity_On_Hand AS Total_Item_Value
FROM   PRODUCT
ORDER BY Purchase_Cost * Quantity_On_Hand DESC

SELECT *
FROM (
    SELECT Product_ID, Product_Name, Purchase_Cost, Quantity_On_Hand, Purchase_Cost * Quantity_On_Hand AS Total_Item_Value
    FROM   PRODUCT
) x
ORDER BY Total_Item_Value DESC