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
SELECT submit_month,montn_q_cnt,round(montn_q_cnt/days,3) FROM ( SELECT ifnull(submit_month,'2021汇总') AS submit_month, montn_q_cnt, day(last_day(if(submit_month IS NULL ,str_to_date('20210131','%Y%m%d'),concat(submit_month,'01')))) days FROM ( SELECT date_format(submit_time,'%Y%m') as submit_month, count(1) montn_q_cnt FROM practice_record WHERE year(submit_time) = '2021' GROUP BY date_format(submit_time,'%Y%m') WITH ROLLUP )t1 )t2 ORDER BY submit_month;
麻瓜思路