इसे आजमाएं:
SELECT
sch.id,
SUM(IF(app.status = 'completed' , 1, 0))
FROM
com_event_schedules sch
INNER JOIN com_event_schedules_com_appointment_c rel
ON rel.com_event_schedules_com_appointmentcom_event_schedules_ida = sch.id
INNER JOIN com_appointment app
ON rel.com_event_schedules_com_appointmentcom_appointment_idb = app.id
GROUP BY
sch.id
HAVING
COUNT(*) > 1
