select
    uv.room_id,
    room_name,
    count(distinct user_id) user_count
from
    user_view_tb uv
    join room_info_tb rit on uv.room_id = rit.room_id
where
    out_time <= '23:59:59'
    and out_time >= '23:00:00'
group by
    uv.room_id,
    room_name
order by
    user_count desc

只需统计退出时间(out_time)在晚上11-12点之间的人次--在线,就行(需去重)