我已经通过这道题！ https://www.nowcoder.com/questionTerminal/46cb7a33f7204f3ba7f6536d2fc04286

select date_format(submit_time,'%Y%m') submit_month,count(*) month_q_cnt,round(count(*)/max(day(last_day(submit_time))),3) avg_day_q_cnt from practice_record where year(submit_time)=2021 group by submit_month UNION all select '2021汇总' submit_month,count(submit_time) month_q_cnt, round(count(*)/31,3...