题解 | #试卷发布当天作答人数和平均分#

select
        b.exam_id
        ,count(distinct b.uid) as uv
        ,round(sum(score)/count(score),1) as avg_score
    from
    (
        select exam_id,date_format(release_time,'%Y%m%d') as release_date
        from examination_info
    ) a
    join
    (
        select *,date_format(start_time,'%Y%m%d') as start_date
        from exam_record
    ) b on a.exam_id=b.exam_id and a.release_date=b.start_date
    left join user_info c on b.uid=c.uid
    where score is not null
    and c.level>5
    group by b.exam_id
    order by uv desc,avg_score

对“作答过”的定义能不能清晰一点...