instruction: Average number of comments per question by score (deleted questions excluded).
response: SELECT COALESCE(Score, 0), AVG(1.0 * COALESCE(CommentCount, 0)) FROM Posts WHERE PostTypeId = 1 AND ABS(COALESCE(Score, 0)) <= 20 GROUP BY COALESCE(Score, 0) ORDER BY COALESCE(Score, 0)