题解 | #月总刷题数和日均刷题数#
月总刷题数和日均刷题数
https://www.nowcoder.com/practice/f6b4770f453d4163acc419e3d19e6746
使用union把2021汇总与原表查询汇总到一起,一开始运行老是报错,找了好久才发现分组后没有处理day (last_day (submit_time)),加了个max就显示本月的最大天数了,后面发现没有这个where实例通过不了. (select date_format (submit_time, '%Y%m') submit_month, count(1) month_q_cnt, ROUND(count(1) / max(day (last_day (submit_time))), 3) avg_day_q_cnt from practice_record where year(submit_time)=2021 group by submit_month) union (select '2021汇总' as submit_month, count(*) submit_month, ROUND(count(*) / max(day (last_day (submit_time))), 3) avg_day_q_cnt from practice_record where year(submit_time)=2021) order by submit_month;