题解 | #统计作答次数#
SQL类别高难度试卷得分的截断平均值
http://www.nowcoder.com/practice/a690f76a718242fd80757115d305be45
SELECT DISTINCT ei.tag,ei.difficulty,ROUND((SUM(er.score)-MAX(er.score)-MIN(er.score))/(COUNT(er.score)-2),1) clip_avg_score FROM examination_info ei JOIN exam_record er ON ei.exam_id=er.exam_id WHERE ei.tag='SQL' AND ei.difficulty='hard'; 主要是聚合函数的使用
