题解 | #浙大不同难度题目的正确率#

select difficult_level, round(sum(case result when 'right' then 1 else 0 end )*1.0/sum(1),4) correct_rate from user_profile a
join question_practice_detail b on a.device_id = b.device_id
join question_detail c on c.question_id = b.question_id
where a.university = "浙江大学"
group by difficult_level 
order by correct_rate asc