oj-sql

题目

SQL131 作答试卷得分大于过80的人的用户等级分布

思路

1. 连表
   1. 对每个表条件筛选
   2. 聚合、排序

solution

join table

select
   user.level,
   count(record.id) as level_cnt
from exam_record record
join examination_info info
on (record.exam_id=info.exam_id)
join user_info user
on (record.uid=user.uid)
where info.tag='SQL'
and record.score >80
group by user.level
order by level_cnt desc
;