计算发货时间超过X天的订单百分比的更好方法？

问题描述

我正在编写一个T-SQL查询来计算发货时间超过X天的订单百分比。

我现在拥有的东西可以工作，但是感觉很笨拙，我一直在寻求提高我的查询编写技能。

第一个CTE从某个时间范围获得总订单。第二个CTE收到任何发货日期比订单日期早3天（或更短）的订单。

;WITH TotalOrders
AS (
SELECT COUNT(*) AS TotalOrders,MONTH(OrderDate) AS Month,YEAR(OrderDate) AS Year
  FROM Orders
 WHERE OrderDate >= '2020-05-01'
GROUP BY MONTH(OrderDate),YEAR(OrderDate)
),Under3
AS (
SELECT COUNT(*) AS Under3Days,YEAR(OrderDate) AS Year
  FROM SorMaster SM
 WHERE OrderDate >= '2020-05-01'
   AND DATEDIFF(D,OrderDate,ShipDate) <= 3
GROUP BY MONTH(OrderDate),YEAR(OrderDate)

)

SELECT ROUND(Under3Days * 100.0 / TPO.TotalOrders,1) AS 'PercentOfTotal',TPO.Month,TPO.Year
  FROM Under3
  JOIN TotalOrders TPO
    ON TPO.Month = Under3.Month
   AND TPO.Year = Under3.Year

我知道我也可以在临时表中执行此操作，但想知道在进行这些计算时是否有最佳实践可以遵循

解决方法

您可以使用条件聚合：

SELECT 
   ROUND(AVG(CASE WHEN ShipDate <= DATEADD(day,3,OrderDate) THEN 100.0 ELSE 0 END),1) AS PercentOfTotal,MONTH(OrderDate) AS Month,YEAR(OrderDate) AS Year
FROM Orders
WHERE OrderDate >= '2020-05-01'
GROUP BY MONTH(OrderDate),YEAR(OrderDate)