题解 | #SQL类别高难度试卷得分的截断平均值#

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