在单行中查询多个聚合

Question

我想要一个查询，在他们自己的专栏中返回3个月，6个月和12个月的结果。

3 | 6 | 12   
V1| V2| V3

我有一个查询，它会给我以下任何一个结果：

获取一个值的代码：

SELECT SUM(CONVERT(bigint,R.FileSize)) / (1024*1024) AS '3' 
FROM Revisions R
JOIN Documents D ON D.DocumentID = R.DocumentID
WHERE R.Date BETWEEN dateadd(month, -3, GETDATE()) AND getdate()

结果： 3 205

我试图嵌入SQL查询并将它们组合起来。

SELECT b.3, SUM(CONVERT(bigint,R.FileSize)) / (1024*1024) AS '6'
FROM Revisions R2
JOIN Documents D2 ON D2.DocumentID = R2.DocumentID
FULL OUTER JOIN b ON b.3 = 6

(SELECT SUM(CONVERT(bigint,R.FileSize)) / (1024*1024) AS '3' 
 FROM Revisions R
 JOIN Documents D ON D.DocumentID = R.DocumentID
 WHERE R.Date BETWEEN dateadd(month, -3, GETDATE()) AND getdate()) b
WHERE R2.Date BETWEEN dateadd(month, -6, GETDATE()) AND getdate();

Answer 1

我想你想要条件聚合：

SELECT SUM(CASE WHEN R.Date BETWEEN dateadd(month, -3, GETDATE()) AND getdate()
                THEN CONVERT(bigint, R.FileSize)) / (1024*1024)
           END) AS filesize_3,
       SUM(CASE WHEN R.Date BETWEEN dateadd(month, -6, GETDATE()) AND getdate()
                THEN CONVERT(bigint, R.FileSize)) / (1024*1024)
           END) AS filesize_6,
       SUM(CASE WHEN R.Date BETWEEN dateadd(month, -9, GETDATE()) AND getdate()
                THEN CONVERT(bigint, R.FileSize)) / (1024*1024)
           END) AS filesize_9        
FROM Revisions R JOIN
     Documents D
     ON D.DocumentID = R.DocumentID