instruction: Closed Questions Count by Month.
response: SELECT date1, COUNT(Id) AS cnt FROM (SELECT TIME_TO_STR(d.CreationDate, '%y-%m') AS "date1", (d.Id) AS id FROM Posts AS d LEFT JOIN PostHistory AS ph ON ph.PostId = d.Id LEFT JOIN PostLinks AS pl ON pl.PostId = d.Id LEFT JOIN Posts AS o ON o.Id = pl.RelatedPostId WHERE d.PostTypeId = 1 AND ph.PostHistoryTypeId = 10) AS t1 GROUP BY date1 ORDER BY date1