题解 | #每篇文章同一时刻最大在看人数#

with t as (
    select artical_id,in_time as dt,1 diff
    from tb_user_log
    where artical_id != 0
    union all
    select artical_id,out_time as dt,-1 diff
    from tb_user_log
    where artical_id != 0
),
t1 as (
    select artical_id,sum(diff) over(partition by artical_id order by dt rows between unbounded preceding and current row) as dd
    from t
)
select artical_id,max(dd) as max_uv
from t1
group by artical_id
order by max_uv desc