题解 | #每个题目和每份试卷被作答的人数和次数#

select *
from (select exam_id             tid
           , count(distinct uid) uv
           , count(start_time)   pv
      from exam_record
      group by exam_id
      order by uv desc, pv desc) as t1
union
select *
from (select question_id         tid
           , count(distinct uid) uv
           , count(submit_time)  pv
      from practice_record
      group by question_id
      order by uv desc, pv desc) as t1;