Q&A for music historians, critics, and fans
select qlist.uid as userId, count(p.Id) as answer_count,AVG(p.Score) as a_score, var(p.Score) as scorevariance, max(p.Score) as maxscore, AVG(p.CommentCount) as a_comment, datediff(month,cast('2015-03-01' as datetime), p.CreationDate) as month from Posts p, (select p.Id as pid, userlist.uid as uid, p.CreationDate as qdate from Posts p, PostTags pt, (select p.OwnerUserId as uid from Posts p, PostTags pt, Users u where p.OwnerUserId=u.Id and p.Id=pt.PostId and (pt.TagId=4190 or pt.TagId=67719 or pt.TagId=20400) and p.PostTypeid=1 and p.CreationDate>=cast('2015-03-01' as datetime) and p.CreationDate<=cast('2017-03-31' as datetime) group by p.OwnerUserId ) userlist where userlist.uid=p.OwnerUserId and p.CreationDate>=cast('2015-03-01' as datetime) and p.CreationDate<=cast('2017-03-31' as datetime) and p.PostTypeId=1 and pt.PostId = p.Id and (pt.TagId=4190 or pt.TagId=67719 or pt.TagId=20400) ) qlist where p.ParentId=qlist.pid and p.PostTypeId=2 group by qlist.uid, datediff(month,cast('2015-03-01' as datetime), p.CreationDate) order by qlist.uid, datediff(month,cast('2015-03-01' as datetime), p.CreationDate)