Q&A for professionals, academics, and students working within the systems development life cycle
SELECT Month = DATEADD(MONTH, DATEDIFF(MONTH, 0, p.CreationDate), 0), 'Up-to-date content' = AVG(DATEDIFF(hour, p1.CreationDate, p.CreationDate)) FROM Posts p INNER JOIN Posts p1 ON p.Id = p1.AcceptedAnswerId GROUP BY DATEADD(MONTH, DATEDIFF(MONTH, 0, p.CreationDate), 0) ORDER BY Month