题解35 | #浙大不同难度题目的正确率# 个人笔记

筛选：浙江大学

分组：不同难度

正确率：作对的题目数量/全部的题目数量 正确率还可以直接用avg计算 avg(if(b.result = 'right',1,0))

排序：准确率升序 asc

表连接：join即可

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