Sql 按查询划分组中的值

如何生成这样的请求（Sql Server 2008 R2）：
（我需要每个结果的“平均价格”）

（如果可能，无需重新计算两个总和的一倍）

或者您可以使用

CTE

WITH cte
AS
(
    SELECT  CategoryId, 
            SUM(Price) AS TotalPrice, 
            SUM(Quantity) AS TotalQuantity
    FROM    Products 
    GROUP   BY CategoryId
)
SELECT CategoryId,
       TotalPrice,
       TotalQuantity,
       TotalPrice / TotalQuantity * 1.0 AveragePrice
FROM   cte

---

没有重新计算

SELECT *, A.TotalPrice / A.TotalQuantity AS AveragePrice
FROM (SELECT 
       CategoryId
       , SUM(Price) AS TotalPrice
       , SUM(Quantity) AS TotalQuantity
      FROM Products 
      GROUP BY CategoryId) AS A

---

试着看看执行计划。

WITH cte
AS
(
    SELECT  CategoryId, 
            SUM(Price) AS TotalPrice, 
            SUM(Quantity) AS TotalQuantity
    FROM    Products 
    GROUP   BY CategoryId
)
SELECT CategoryId,
       TotalPrice,
       TotalQuantity,
       TotalPrice / TotalQuantity * 1.0 AveragePrice
FROM   cte

SELECT *, A.TotalPrice / A.TotalQuantity AS AveragePrice
FROM (SELECT 
       CategoryId
       , SUM(Price) AS TotalPrice
       , SUM(Quantity) AS TotalQuantity
      FROM Products 
      GROUP BY CategoryId) AS A