题解 | #各用户等级的不同得分表现占比#

with t as
(select level,score,count(level)over(partition by level) as level_cn,
(case when score<60 then '差'
when score<75 and score>=60 then '中'
when score<90 and score>=75 then '良'
else '优' end) as grade
from exam_record
left join user_info
using(uid)
where score is not null)


select level,grade,round(count(level)/level_cn,3) as ratio
from t
group by level,grade
order by level desc,ratio desc