题解 | #每篇文章同一时刻最大在看人数#

with t1 as (
    select
        artical_id,
        in_time as at_time,
        1 as uv
    from
        tb_user_log 
        where artical_id!=0
    union all
    select
        artical_id,
        out_time as at_time,
        -1 as uv
    from
        tb_user_log
  where artical_id!=0
),
t2 as(
    select
        artical_id,
        sum(uv) over (
            partition by artical_id
            order by
                at_time,
                uv desc
        ) as current_uv
    from
        t1
)

select
    artical_id,
    max(current_uv) as max_uv
from
    t2
group by
    artical_id
order by
    max_uv desc