我对这个答案并不感到骄傲，但它应该可以工作:

I'm not super proud of this answer, but it should work:

SELECT 0 as is_total, CONCAT(u.lastname, ', ', u.firstname) AS Name, start.timestamp start, end.timestamp end, timediff(end.timestamp, start.timestamp) duration 
    from user u, user_group ug, (
    select *, (
        select event_id from event L2 where L2.timestamp>L1.timestamp and L2.user_bannerid=L1.user_bannerid order by timestamp limit 1
    ) stop_id from event L1
) start join event end on end.event_id=start.stop_id
where start.status='In' and end.status='Out' and u.user_bannerid = start.user_bannerid and ug.user_bannerid = u.user_bannerid  and ug.group_id = start.group_id 

UNION
SELECT 1, null, null, null, sum(duration)
FROM
(
    SELECT CONCAT(u.lastname, ', ', u.firstname) AS Name, start.timestamp start, end.timestamp end, timediff(end.timestamp, start.timestamp) duration 
        from user u, user_group ug, (
        select *, (
            select event_id from event L2 where L2.timestamp>L1.timestamp and L2.user_bannerid=L1.user_bannerid order by timestamp limit 1
        ) stop_id from event L1
    ) start join event end on end.event_id=start.stop_id
    where start.status='In' and end.status='Out' and u.user_bannerid = start.user_bannerid and ug.user_bannerid = u.user_bannerid  and ug.group_id = start.group_id 

) total
ORDER BY is_total