Q&A about the site for expert genealogists and people interested in genealogy or family history
SELECT date1 as creationDate, AVG(diff1) as avgDaysToClose FROM ( SELECT DATEDIFF(day, d.CreationDate, d.ClosedDate) as [diff1], FORMAT (d.CreationDate, 'yy-MM') as [date1], FORMAT (d.ClosedDate, 'yy-MM') as [date2], (d.Id) as id FROM Posts d LEFT JOIN PostHistory ph ON ph.PostId = d.Id LEFT JOIN PostLinks pl ON pl.PostId = d.Id LEFT JOIN Posts o ON o.Id = pl.RelatedPostId -- o=original WHERE d.PostTypeId = 1 -- 1=Question AND pl.LinkTypeId = 3 -- 3=duplicate AND ph.PostHistoryTypeId = 10 -- 10=Post Closed ) as t1 group by date1 order by date1