Plots total questions over time or total score over time, comparing up to 4 tags. Reference: http://meta.stackoverflow.com/q/260570/331508
Q&A for professional and enthusiast programmers
DECLARE @ShowScore INT = 1; WITH QuestStatsByMonth AS ( SELECT DATEADD (month, DATEDIFF (month, 0, q.CreationDate), 0) AS [Month], t.TagName, SUM (q.Score) AS TotalScore, COUNT (q.Id) AS NumQuests FROM Posts q INNER JOIN PostTags pt ON q.Id = pt.PostId INNER JOIN Tags t ON t.Id = pt.TagId WHERE q.PostTypeId = 1 AND t.TagName IN ('angular', 'reactjs', 'jquery') GROUP BY DATEADD (month, DATEDIFF (month, 0, q.CreationDate), 0), t.TagName ) SELECT q.[Month], CASE @ShowScore WHEN 1 THEN q.TagName + ' score' ELSE q.TagName + ' questions' END AS [Tag], CASE @ShowScore WHEN 1 THEN SUM (h.TotalScore) ELSE SUM (h.NumQuests) END AS Cumulative FROM QuestStatsByMonth q LEFT JOIN QuestStatsByMonth h ON h.[Month] = q.[Month] AND h.TagName = q.TagName GROUP BY q.[Month], q.TagName ORDER BY q.[Month], q.TagName