题解 | 输出播放量最高的视频

with a as (select cid,start_time dt,1 stage from play_record_tb
union all
select cid,end_time dt,-1 from play_record_tb
),
b as (
    select
        cid,
        sum(stage) over (partition by cid order by dt) csum
    from
        a)
select
    cid,
    round(max(csum),3) max_peak_uv
from
    b
group by 
    cid
order by 
    max_peak_uv desc
limit 3