-- 11月
-- 每天
-- 人均浏览文章时长
-- 浏览人数
-- 浏览文章时长和

SELECT date(out_time),round(sum(TIMESTAMPDIFF(second,in_time,out_time))/count(distinct uid),1) avg_view_len_sec
from tb_user_log
where artical_id != 0 and month(out_time)=11
group by date(out_time)
order by avg_view_len_sec asc

比较简单