WITH attend AS ( SELECT user_id, course_id, in_datetime time, 1 tmp FROM attend_tb UNION ALL SELECT user_id, course_id, out_datetime , -1 FROM attend_tb ), -- 打标,进为+1,出为-1 nums AS( SELECT course_id, SUM(tmp) OVER(PARTITION BY course_id ORDER BY time) num FROM attend ), -- 分科目按时间序列计算直播间实时人数 max_nums ...