with t1 as (
    select uid,substr(in_time,1,10) as dt,
           (unix_timestamp(out_time) - unix_timestamp(in_time)) as toltime

    from tb_user_log
    where substr(in_time,1,7) = '2021-11' and artical_id != 0
),
t2 as (
        select dt,uid,sum(toltime) as tol1
        from t1
        group by dt,uid
    ),
t3 as (
    select dt,count(distinct uid) as renshu,sum(tol1) as tol2 from t2 group by dt
    )
select dt, round(tol2/renshu,1) as avg_viiew_len_sec  from t3 order by avg_viiew_len_sec