题解 | #作答试卷得分大于过80的人的用户等级分布#

有个坑，需要加上排序user_info.level desc;

select level,
count(distinct user_info.uid) as level_cnt
from exam_record
left join examination_info using(exam_id)
left join user_info using(uid)
where examination_info.tag = 'SQL' and exam_record.submit_time is not null
and exam_record.score > 80 
group by user_info.level
order by level_cnt desc,user_info.level desc;