MySQL, MySQL - rextester

Language: Layout:

drop table a8;
create table a8(id integer,start datetime,ende datetime);
insert into a8(id, start, ende) values (1, '2018-5-15T10:00','2018-5-15T20:44');
insert into a8(id, start, ende) values (1, '2018-5-16T10:00','2018-5-16T20:44');
insert into a8(id, start, ende) values (1, '2018-6-16T10:00','2018-6-16T11:01');
insert into a8(id, start, ende) values (1, '2018-6-17T10:00','2018-6-17T11:01');
insert into a8(id, start, ende) values (1, '2018-7-10T16:00','2018-7-10T17:59');
insert into a8(id, start, ende) values (1, '2018-7-17T16:00','2018-7-17T17:59');
insert into a8(id, start, ende) values (1, '2018-7-18T16:00','2018-7-18T17:59');
insert into a8(id, start, ende) values (1, '2018-8-17T16:00','2018-8-17T17:59');

select 
sum(time_to_sec(timediff(ende,start))) Sekunden,
truncate(sum(time_to_sec(timediff(ende,start)))/3600,0) Stunden,
truncate(
    (sum(time_to_sec(timediff(ende,start))) - truncate(sum(time_to_sec(timediff(ende,start)))/3600,0) * 3600)
/60,0) Minuten
from a8
group by start;


absolute service time: 0,36 sec