總和同一列不同的方式

Question

這裏的月產量報告我的表PROD：

PruID Prod1 Prod2, ReportDate 
001 12.5 32.4 1/1/1999 
001 13.0 32.0 2/1/1999 
... 
002 45.2 32.4 1/1/2004 
002 56.3 43.2 2/1/2004 
... 

我想總結PROD1和Prod2的，以及過去12個月PROD1 & Prod2的由PruID。我寫了2個獨立的查詢，他們正在針對各種用途：

查詢1：總結PROD1 & Prod2的由PruID

SELECT Prod.PruID, Sum(Prod.Prod1) AS CumProd1, Sum(Prod.Prod2) AS CumProd2 
FROM Prod 
GROUP BY Prod.PruID; 

查詢2：總結過去12個月PROD1 &的Prod2的由PruID

SELECT PruID, Sum(Prod1) AS Cum12MonProd1, Sum(Prod2) AS Cum12MonProd2 
FROM Prod 
WHERE Prod.ReportDate > DATEADD('m', -12, now()) 
GROUP BY PruID; 

如何將2個查詢結合一體，以生產這樣的事情：

PruID CumProd1 CumProd2 Cum12MonProd1 Cum12MonProd2 

Answer 1

這裏的訣竅是從sum函數的第二個查詢中篩選出過濾出的數據。

SELECT prod.pruid, 
     SUM (prod.prod1) AS cumprod1, 
     SUM (prod.prod2) AS cumprod2, 
     SUM (
      CASE 
       WHEN prod.reportdate > dateadd ('m', -12, now()) THEN 
        prod.prod1 
       ELSE 
        NULL 
      END) 
      AS cum12monprod1, 
     SUM (
      CASE 
       WHEN prod.reportdate > dateadd ('m', -12, now()) THEN 
        prod.prod2 
       ELSE 
        NULL 
      END) 
      AS cum12monprod2 
FROM  prod 
GROUP BY prod.pruid; 

Answer 2

你既可以JOIN兩個子查詢：

SELECT a.PurID, a.CumProd1, a.CumProd2, b.Cum12MonProd1, b.Cum12MonProd2 
FROM 
(

    SELECT Prod.PruID, Sum(Prod.Prod1) AS CumProd1, Sum(Prod.Prod2) AS CumProd2 
    FROM Prod 
    GROUP BY Prod.PruID 
) a INNER JOIN 
(

    SELECT PruID, Sum(Prod1) AS Cum12MonProd1, Sum(Prod2) AS Cum12MonProd2 
    FROM Prod 
    WHERE Prod.ReportDate > DATEADD('m', -12, now()) 
    GROUP BY PruID 
) b 
ON a.PruID = b.PruID; 

或在第二組款項使用CASE：

SELECT 
    Prod.PruID, 
    Sum(Prod.Prod1) AS CumProd1, 
    Sum(Prod.Prod2) AS CumProd2, 
    Sum(CASE WHEN Prod.ReportDate > DATEADD('m', -12, now()) THEN Prod1 ELSE 0) AS Cum12MonProd1, 
    Sum(CASE WHEN Prod.ReportDate > DATEADD('m', -12, now()) THEN Prod2 ELSE 0) AS Cum12MonProd2 
FROM Prod 
GROUP BY Prod.PruID;