题解 | #作答试卷得分大于过80的人的用户等级分布#

select 
c.level,
count(c.level) level_cnt
from 
exam_record a,
examination_info b,
user_info c
where a.exam_id=b.exam_id
and a.uid=c.uid
and b.tag='SQL'
and a.score is not null
and a.score>80
group by c.level
order by level_cnt desc