题解 | 短视频直播间晚上11-12点之间各直播间的在线人数

select room_info_tb.room_id,room_name,user_count
from room_info_tb join (select room_id,count(distinct user_id) as user_count
from user_view_tb
where hour(out_time) >= 23
group by room_id) as ts on room_info_tb.room_id = ts.room_id

#直接找出11点-12点间各直播间在线人数

select room_id,count(distinct user_id) as user_count

from user_view_tb

where hour(out_time) >= 23

group by room_id

#两表连接