Zkuste toto:
select t4.AppointmentTimeID, t4.AppointmentDate,ifnull(t5.NumberOfApplicants,0)
from
(select distinct t2.AppointmentTimeID, t1.AppointmentDate
from tbl_appointmentschedule_details t2 join (select t.AppointmentDate from (
SELECT adddate('2015-10-16', @rownum := @rownum + 1) as 'AppointmentDate' FROM tbl_appointments
JOIN (SELECT @rownum := -1) r
LIMIT 31
) t
where t.AppointmentDate between '2015-10-16' and '2015-10-18') t1) t4
left join
(SELECT t2.AppointmentTimeID,t1.AppointmentDate,sum(t1.NumberOfApplicants) as 'NumberOfApplicants'
FROM tbl_appointmentschedule_details t2
LEFT JOIN tbl_appointments t1 on t2.AppointmentTimeID=t1.AppointmentTimeID
WHERE t1.AppointmentStatus='Pending' AND t1.AvailableInMarket=0
GROUP BY t2.AppointmentTimeID,t1.AppointmentDate) t5
on t4.AppointmentDate=t5.AppointmentDate and t4.AppointmentTimeID=t5.AppointmentTimeID
having t4.AppointmentTimeID!=0
order by t4.AppointmentDate,t4.AppointmentTimeID;