题解 | #SQL类别高难度试卷得分的截断平均值#

select tag, difficulty, round(avg(score),1) as clip_avg_score FROM( exam_record as er left join examination_info as ei on er.exam_id = ei.exam_id ) where tag = 'SQL' and difficulty = 'hard' and score not in ( select max(score) FROM exam_record as er left join examination_info as ei on er.exam_id = ei.exam_id where tag = 'SQL' and difficulty = 'hard' ) and score not in ( select min(score) FROM exam_record as er left join examination_info as ei on er.exam_id = ei.exam_id where tag = 'SQL' and difficulty = 'hard' )