题解 | 每篇文章同一时刻最大在看人数

select artical_id,max(num) max_uv from(
select artical_id,sum(sign)over(partition by artical_id order by time,sign desc) num
from(
select artical_id,in_time as time,1 as sign
from tb_user_log
where artical_id != 0

union all

select artical_id,out_time as time,-1 as sign
from tb_user_log
where artical_id != 0) as t1) as t2
group by artical_id
order by max_uv desc