Q&A for professional and enthusiast programmers
-- Time series of the number of active experts per week
-- Where "active expert" is someone who has posted more than one upvoted answer.
-- Per Deer Hunter's definition in http://meta.stackexchange.com/a/261608/
-- X-axis is in years, so the point at 2015.0 is the first week of 2015.
DECLARE @tag nvarchar(150)
SET @tag = '##tagName##'
select YR_WK, count(*) as NumActiveExperts
(datepart(yy, p.creationdate) + (datepart(wk, p.creationdate)-1) / 52.0) as YR_WK
, u.id as UID
, count (*) as NumAnswers
from users u
inner join posts p
p.owneruserid = u.id
and p.posttypeid = 2
and p.score > 0
inner join posts q
p.ParentId = q.id
and q.posttypeid = 1
and q.tags LIKE CONCAT('%', '@tag', '%')
(datepart(yy, p.creationdate) + (datepart(wk, p.creationdate)-1) / 52.0)
where NumAnswers > 1
group by YR_WK
order by YR_WK asc