create table ring_event (
ring_event_id   integer,
event_name      varchar(20)
ring_id         integer references ring(ring_id),
start_time      time,
time_per_dog    time,
);
-- you can then use 
select a.ring_event_id, a.event_name,
       a.ring_id, a.start_time, 
       ADDTIME(a.start_time, time_per_dog * count(b.dog_id))
         as end_time, count(b.dog_id) as num_dogs
 from ring_event a, tda b
 where a.ring_event_id = b.ring_event_id 
 group by a.ring_event_id;
-- to get the end_time and number of dogs.