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
- 试卷表和考试记录表内连接
- 内连接还可以写作：join examination_info using(exam_id)；
SELECT tag, difficulty,
round((sum(er.score) - max(er.score) - min(er.score)) / (count(er.score)-2), 1) as clip_avg_score
FROM examination_info ei
JOIN exam_record er ON ei.exam_id = er.exam_id
WHERE tag ="SQL" and difficulty = "hard";
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