题解 | #确定最佳顾客的另一种方式（二）#

两个版本都可以通过

• 版本一 用AVG函数 select date_format(submit_time,'%Y%m') submit_month, count(question_id) month_q_cnt, round(count(question_id)/ AVG(day(LAST_DAY(submit_time))),3) avg_day_q_cnt from practice_record where date_format(submit_time,'%Y')='2021' group by submit_month union all select '2021汇总' as submit_month, count(question_id) month_q_cnt, round(count(id)/31,3) avg_day_q_cnt from practice_record where date_format(submit_time,'%Y')='2021' order by submit_month;

• 版本二 用any_value select date_format(submit_time,'%Y%m') submit_month, any_value(count(question_id)) month_q_cnt, any_value(round(count(question_id)/day(LAST_DAY(submit_time)),3)) avg_day_q_cnt from practice_record where date_format(submit_time,'%Y')='2021' group by submit_month union all select '2021汇总' as submit_month, count(question_id) month_q_cnt, round(count(id)/31,3) avg_day_q_cnt from practice_record where date_format(submit_time,'%Y')='2021' order by submit_month;