题解 | #浙大不同难度题目的正确率#

SELECT
    qd.difficult_level,
    IFNULL (SUM(qp.result = 'right') / COUNT(*), 0) AS accuracy_rate
FROM
    user_profile up
    JOIN question_practice_detail qp ON up.device_id = qp.device_id
    JOIN question_detail qd ON qp.question_id = qd.question_id
WHERE
    up.university = '浙江大学'
GROUP BY
    qd.difficult_level
ORDER BY
    accuracy_rate;