select course_id, course_name, max(cnt)as max_num from(select course_id, course_name, sum(flag) over(partition by course_id order by event_time) as cnt from(select at.course_id, ct.course_name, date_format(ct.course_datetime, '%Y-%m-%d %H:%i:00') as start_time, date_format(concat(date_format(ct.cour...