题解 | #每篇文章同一时刻最大在看人数#

select artical_id,
       max(sum_uv) max_uv
from(
    select artical_id,
       sum(flag)over(partition by artical_id order by td,flag desc) sum_uv
    from(
        select artical_id,in_time td,1 flag
        from tb_user_log
        where artical_id<>0
        union all
        select artical_id,out_time, -1 flag
        from tb_user_log
        where artical_id<>0
    )t1
)t2
group by artical_id
order by max_uv desc