Coba ini:
rel.com_event_schedules sch.id, SUM(IF(app.status ='completed' , 1, 0)) DARI com_event_schedules schINNER GABUNG com_event_schedules_com_appointment_c rel ON rel.com_event_schedules_com_appointmentJO_event_event =app.id GROUP OLEH sch.idHAVING COUNT(*)> 1