#  踩坑
-- 1. avg(timestampdiff(second,in_time,out_time))算的是次均浏览时长，应该算人均，人有重复。总时长/用户数
-- 2. 未排除artical_id=0


select 
  date(in_time) dt,
  round(sum(timestampdiff(second,in_time,out_time))/(count(distinct uid)),1) as avg_viiew_len_sec
from tb_user_log
where date_format(in_time,"%Y%m") = "202111"
and artical_id  != 0
group by dt
order by avg_viiew_len_sec asc