SQL select 语句,根据其他列计算列
SQL select statement, calculating columns based on other columns
我正在尝试汇总各个价格并使用折扣逻辑。
SELECT O.OrderID,
if(C.IsClubMember & OrderNumber % 10 = 0, 0.5 * Sum(I.ItemPrice), Sum(I.ItemPrice)) as Price,
0.07*Price as Tax, Price + Tax as Total
FROM Orders as O JOIN ItemPriceView as I
ON O.OrderID = I.OrderID JOIN Customer as C
ON O.CustomerID = C.CustomerID
GROUP BY OrderID
我遇到一个错误:
Error Code: 1054. Unknown column 'Price' in 'field list'
编写查询的正确方法是什么?
一种解决方案是使用子查询计算价格,然后在外部查询中计算税金和总计。
这应该有效:
SELECT OrderID, Price, 0.07*Price as Tax, 1.07*Price as Total
FROM
(
SELECT O.OrderID as OrderID,
if(C.IsClubMember & OrderNumber % 10 = 0, 0.5 * Sum(I.ItemPrice),Sum(I.ItemPrice)) as Price
FROM Orders as O JOIN ItemPriceView as I
ON O.OrderID = I.OrderID JOIN Customer as C
ON O.CustomerID = C.CustomerID
GROUP BY OrderID
) as sub_query
我正在尝试汇总各个价格并使用折扣逻辑。
SELECT O.OrderID,
if(C.IsClubMember & OrderNumber % 10 = 0, 0.5 * Sum(I.ItemPrice), Sum(I.ItemPrice)) as Price,
0.07*Price as Tax, Price + Tax as Total
FROM Orders as O JOIN ItemPriceView as I
ON O.OrderID = I.OrderID JOIN Customer as C
ON O.CustomerID = C.CustomerID
GROUP BY OrderID
我遇到一个错误:
Error Code: 1054. Unknown column 'Price' in 'field list'
编写查询的正确方法是什么?
一种解决方案是使用子查询计算价格,然后在外部查询中计算税金和总计。
这应该有效:
SELECT OrderID, Price, 0.07*Price as Tax, 1.07*Price as Total
FROM
(
SELECT O.OrderID as OrderID,
if(C.IsClubMember & OrderNumber % 10 = 0, 0.5 * Sum(I.ItemPrice),Sum(I.ItemPrice)) as Price
FROM Orders as O JOIN ItemPriceView as I
ON O.OrderID = I.OrderID JOIN Customer as C
ON O.CustomerID = C.CustomerID
GROUP BY OrderID
) as sub_query