with T as(select exam_id,avg(score)as av,avg(timestampdiff(second,start_time,submit_time))as at from exam_record group by exam_id) select emp_info.emp_id,emp_info.emp_level,examination_info.tag as exam_tag from emp_info,examination_info,(select emp_id,exam_id from exam_record left join T using(exam_...