题解 | #每篇文章同一时刻最大在看人数#

with log as 
(
    select
    tb_user_log.uid
    ,tb_user_log.artical_id
    ,tb_user_log.in_time time
    ,1 as is_in
    from tb_user_log
    where artical_id != 0
    union all
    select
    tb_user_log.uid
    ,tb_user_log.artical_id
    ,tb_user_log.out_time time
    ,-1 as is_in
    from tb_user_log
    where artical_id != 0
)


select
artical_id
,max(uv)
from
(
select artical_id
,time
,sum(is_in) over (partition by artical_id order by time, is_in desc) uv
from log
) t
group by artical_id
order by max(uv) desc