题解 | #月总刷题数和日均刷题数#

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

union all
(select
'2021汇总' as submit_month,
count(*) as month_q_cnt,
round(count(*)/31,3) as avg_day_q_cnt
from practice_record
where year(submit_time) = 2021
)
order by submit_month



# 不理解这个年刷题总数除以31是什么意思，有人看得懂吗？