使用Windows函数+分区按2列计算百分比

Question

我正在尝试编写查询，为每个客户计算其当年总利润的一部分。

我通过使用join来编写此查询，但是我想通过Windows函数+分区来编写此查询。

SELECT t1.Customer_ID, t1.Year, [Sum of Profit]/[Total Profit] [Part of Profit]
FROM
(SELECT Customer_ID, DATEPART(YEAR, Order_Date) Year, 
SUM(Try_convert(float,Profit)) [Sum of Profit]
FROM Orders
GROUP BY Customer_ID, DATEPART(YEAR, Order_Date)) t1
JOIN
(SELECT DATEPART(YEAR, Order_Date) Year, SUM(Try_convert(float,Profit)) [Total Profit]
FROM Orders
GROUP BY DATEPART(YEAR, Order_Date)) t2
ON t1.Year = t2.Year

如何使用Windows函数+分区进行相同的查询？

Answer 1

您可以在聚合查询中使用窗口函数：

SELECT Customer_ID, YEAR(Order_Date) as Year, 
       SUM(Try_convert(float, Profit)) as [Sum of Profit],
       (SUM(Try_convert(float, Profit)) /
        SUM(SUM(Try_convert(float, Profit))) OVER ()
       ) as ratio
FROM Orders
GROUP BY Customer_ID, YEAR(Order_Date)