题解 | #浙大不同难度题目的正确率#
浙大不同难度题目的正确率
https://www.nowcoder.com/practice/d8a4f7b1ded04948b5435a45f03ead8c
SELECT qd.difficult_level,(
SUM(CASE WHEN qpd.result='right' THEN 1
ELSE 0
END
)/COUNT(qpd.result)
) correct_rated
FROM user_profile up,
question_practice_detail qpd,
question_detail qd
WHERE up.university='浙江大学'
AND up.device_id=qpd.device_id
AND qpd.question_id=qd.question_id
GROUP BY qd.difficult_level
order by correct_rated asc
SUM(CASE WHEN qpd.result='right' THEN 1
ELSE 0
END
)/COUNT(qpd.result)
) correct_rated
FROM user_profile up,
question_practice_detail qpd,
question_detail qd
WHERE up.university='浙江大学'
AND up.device_id=qpd.device_id
AND qpd.question_id=qd.question_id
GROUP BY qd.difficult_level
order by correct_rated asc
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