# 统计作答 SQL 类别的试卷的分大于过 80 的用户等级分布,数量降序排序 # 思路: # 1. 先筛选出 SQL 类别的试卷 # 2. 查询作答记录表,筛选出用户 # 3. 查询用户表获取用户等级 select level, count(distinct ui.uid) as level_cnt from exam_record er inner join user_info ui on er.uid = ui.uid where er.exam_id in( select exam_id from examination_info where tag = ...