题解 | SQL类别高难度试卷得分的截断平均值

SELECT
    tag,
    difficulty,
    ROUND(avg(score), 1)
FROM examination_info JOIN exam_record
ON examination_info.exam_id= exam_record.exam_id
WHERE tag = "SQL"
AND score IS NOT NULL
AND difficulty = "hard"
AND score NOT IN (select MIN(score) FROM exam_record where exam_id = "9001")
AND score NOT IN (select MAX(score) FROM exam_record where exam_id = "9001")
GROUP BY exam_record.exam_id