题解 | #浙大不同难度题目的正确率#

select
    difficult_level,
    sum(result = 'right')/count(*) correct_rate
from
    question_practice_detail
    left join question_detail on question_detail.question_id = question_practice_detail.question_id
    left join user_profile on user_profile.device_id = question_practice_detail.device_id
    where university='浙江大学'
group by
    difficult_level
order by
    avg(result = 'right');