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
http://www.nowcoder.com/practice/a690f76a718242fd80757115d305be45
保留一位 (count（ss）,1)
select tag, difficulty,
round((sum(score) - max(score) - min(score)) / (count(score) - 2), 1) as clip_avg_score
from exam_record
join examination_info using(exam_id)
where tag = 'SQL' and difficulty = 'hard';
