sql - 无法按外部顺序引用子查询列

Question

以下ORDER BY子句导致错误。如何在ORDER BY子句中引用 TotalPrice 列：

SELECT * FROM
(

SELECT O.OrderID,
       (SELECT SUM(SubTotal) FROM DB_OrderDetails OD WHERE OD.OrderID = O.OrderID) AS TotalPrice,
       ROW_NUMBER() OVER (ORDER BY TotalPrice) AS RowNum

    FROM DB_Orders O

) Orders

Answer 1

你不能在同一个子查询中通过它的名字来引用它，你可以在外部查询中这样做：

SELECT orders.*, 
       ROW_NUMBER() OVER (ORDER BY TotalPrice) AS RowNum FROM
(
    SELECT O.OrderID,
       (SELECT SUM(SubTotal) FROM DB_OrderDetails OD 
        WHERE OD.OrderID = O.OrderID) AS TotalPrice
    FROM DB_Orders O
) Orders

Answer 2

这个怎么样：

select 
    o.orderID,
    sum(od.SubTotal) as TotalPrice,
    row_number() over (order by sum(od.SubTotal)) as RowNum
from DB_Orders o
join DB_OrderDetails od
    on o.OrderID = od.OrderID
group by o.OrderID

这是示例：SQL Fiddle