题解 | 作答试卷得分大于过80的人的用户等级分布
select ui.level level, count(distinct ui.uid) level_cnt from test.user_info ui join test.exam_record er on ui.uid = er.uid join test.examination_info ei on er.exam_id = ei.exam_id where tag = 'SQL' and score > 80 group by ui.level order by level_cnt desc, level desc