instruction: Question per Day on StackExchange.
response: SELECT Date AS "dates", ROUND((SUM(pd.Questions) * 1.00 / COUNT(pd.Date)), 2) AS "questions_per_day" FROM (SELECT SUM(CASE WHEN p.PostTypeId = 1 THEN 1 ELSE 0 END) AS "questions", DATE(p.CreationDate) AS "date" FROM Posts AS p GROUP BY DATE(p.CreationDate)) AS pd GROUP BY Date ORDER BY Date DESC