select ifnull(a,'2021汇总'), month_q_cnt, avg_day_q_cnt from( select date_format(submit_time,'%Y%m') a, count(score) month_q_cnt, round(count(score)/MAX(DAY(last_day(submit_time))),3) avg_day_q_cnt from practice_record where year(submit_time)=2021 group by a with rollup) as tb1