คุณภาพของเนื้อหา จำนวนโหวตโดยเฉลี่ย ไม่จำเป็นต้องใช้ตารางทั้งหมด
Quality of content Average amount of upvotes.It is not neccessary to use all the tables.
 PostLinks:  Id [ number]  CreationDate [ time]  PostId [ number]  RelatedPostId [ number]  LinkTypeId [ number] 
SELECT Month = DATEADD(MONTH, DATEDIFF(MONTH, 0, CreationDate), 0), 'Average amount of upvotes' = SUM(CASE WHEN VoteTypeId = 2 THEN 1 ELSE 0 END) / CAST(COUNT(Id) AS FLOAT) FROM PostFeedback GROUP BY DATEADD(MONTH, DATEDIFF(MONTH, 0, CreationDate), 0) ORDER BY DATEADD(MONTH, DATEDIFF(MONTH, 0, CreationDate), 0)