select

    c.emp_id,

    e.emp_level,

    d.exam_tag

from

    exam_record as c

    join (

        select

            a.exam_id,

            b.tag as exam_tag,

            avg(timestampdiff (second, a.start_time, a.submit_time)) as        avg_time,

            avg(a.score) as avg_score

        from

            exam_record as a

            join examination_info as b on a.exam_id = b.exam_id

        group by

            a.exam_id,

            b.tag

        ) as d on c.exam_id = d.exam_id

    join emp_info as e on c.emp_id = e.emp_id

where

    timestampdiff (second, c.start_time, c.submit_time) < d.avg_time

    and c.score > d.avg_score

    and e.emp_level < 7

order by

    c.emp_id,

    c.exam_id