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