题解 | #某乎问答11月份日人均回答量#

select
    answer_date,
    round(count(issue_id) / count(distinct author_id),2) as per_num
from
    answer_tb
where 
    year(answer_date) = 2021 and month(answer_date) = 11
group by 
    1
order by 
    1