题解 | #浙大不同难度题目的正确率#

1h到10min差点一次正确，忘了排序了最开始

select
    qd.difficult_level difficult_level,
    sum(if (result = 'right', 1, 0)) / count(result) correct_rate
from
    question_practice_detail qp
    left join user_profile u on qp.device_id = u.device_id
    left join question_detail qd on qp.question_id = qd.question_id
where
    u.university = '浙江大学'
group by
    qd.difficult_level
    order by correct_rate