select date_format(in_time,'%Y-%m-%d') as dt,
       round(sum(timestampdiff(second,in_time,out_time))/count(distinct uid),1)
       as avg_viiew_len_Sec
from tb_user_log
where year(in_time)=2021 and month(in_time)=11 and artical_id!=0
group by dt
order by avg_viiew_len_Sec asc