จำนวนคำตอบที่โพสต์และยอมรับทั้งหมดเป็นรายเดือนและปี ไม่จำเป็นต้องใช้ตารางทั้งหมด
Total posted and accepted answers by month and year.It is not neccessary to use all the tables.
 PostTags:  PostId [ number]  TagId [ number] 
SELECT YEAR(a.CreationDate) AS "year", MONTH(a.CreationDate) AS "month", COUNT(*) AS "number_of_answers", (SELECT COUNT(*) AS "number_of_answers" FROM Posts AS aa JOIN Posts AS qq ON aa.ParentId = qq.Id INNER JOIN Users ON Users.Id = aa.OwnerUserId WHERE (aa.PostTypeId = 2 AND qq.AcceptedAnswerId = aa.Id) AND MONTH(aa.CreationDate) = MONTH(a.CreationDate) AND YEAR(aa.CreationDate) = YEAR(a.CreationDate)) AS "number_of_accepted_answers" FROM Posts AS a INNER JOIN Users ON Users.Id = a.OwnerUserId GROUP BY MONTH(a.CreationDate), YEAR(a.CreationDate) ORDER BY YEAR(a.CreationDate), MONTH(a.CreationDate) DESC