Si vous voulez que les valeurs soient sur une seule ligne, vous pouvez faire ceci :
select max(playtime), min(playtime), avg(playtime)
from yourtable
group by mediaid;
Si vous les voulez dans des lignes séparées, utilisez un UNION ALL :
select max(playtime) playtime, mediaid, 'Max' Type
from yourtable
group by mediaid
union all
select min(playtime) playtime, mediaid, 'Min'
from yourtable
group by mediaid
union all
select avg(playtime) playtime, mediaid, 'Avg'
from yourtable
group by mediaid
order by mediaid, playtime;
voir SQL Fiddle avec démo
Modifier #1, en utilisant vos exemples de données ajoutées :
select m.medTitle,
min(TIMESTAMPDIFF(SECOND, s.dmtViewStart, s.dmtViewEnd)) playtime
from tbldoctormediatracktest s
left join tblmedia m
on s.MedId = m.MedId
group by m.medTitle
union all
select m.medTitle,
avg(TIMESTAMPDIFF(SECOND, s.dmtViewStart, s.dmtViewEnd)) playtime
from tbldoctormediatracktest s
left join tblmedia m
on s.MedId = m.MedId
group by m.medTitle
union all
select m.medTitle,
max(TIMESTAMPDIFF(SECOND, s.dmtViewStart, s.dmtViewEnd)) playtime
from tbldoctormediatracktest s
left join tblmedia m
on s.MedId = m.MedId
group by m.medTitle
order by medTitle, playtime
