题解 | #SQL类别高难度试卷得分的截断平均值#
SQL类别高难度试卷得分的截断平均值
https://www.nowcoder.com/practice/a690f76a718242fd80757115d305be45
select tag, difficulty, round((sum(score) - min(score) - max(score))/(count(score)-2),1) from ( select examination_info.tag, examination_info.difficulty, exam_record.score from examination_info, exam_record where examination_info.exam_id = exam_record.exam_id ) as newform group by tag, difficulty having tag = 'SQL' and difficulty = 'hard'
本题难度在于取平均数,需要先将两个表通过exam_id内连接,之后通过聚合函数将总数sum()去除min()最小值和max()最大值除以计数count()-2