题解 | #月总刷题数和日均刷题数#

with temp as (select date_format(submit_time, '%Y%m') as submit_month
                   , count(question_id)               as c
              from practice_record
              where year(submit_time) = '2021'
              group by submit_month)
select submit_month
     , c                                                       as month_q_cnt
     , round(c / day(last_day(concat(submit_month, '01'))), 3) as avg_day_q_cnt
from temp
union
select '2021汇总'            as submit_month
     , sum(c)                as month_q_cnt
     , round(sum(c) / 31, 3) as avg_day_q_cnt
from temp
order by submit_month;