public List<GymClass> getClassesByInstructor(Instructor ins) { List<GymClass> gymClass = new List<GymClass>(); string query = "Select * FROM activity INNER JOIN instactor_activity ON activity.id = instactor_activity.activity_id WHERE instactor_activity.activityTrainer_id ='" + ins.getDBid() + "';"; MySqlCommand cmd = new MySqlCommand(query, this.connection); MySqlDataReader dataReader = cmd.ExecuteReader(); while (dataReader.Read()) { String gymClass_name = (String)dataReader["activity_name"]; int gymClass_capaity = (int)dataReader["capacity"]; int gymClass_listed = (int)dataReader["listed"]; String timeHour = (String)dataReader["timeHour"]; String timeDay = (String)dataReader["timeDay"]; String classRoom = (String)dataReader["room_number"]; Instructor classInstructor = ins; GymClass gc = new GymClass(timeHour, timeDay, gymClass_name, classRoom, gymClass_capaity, gymClass_listed, classInstructor); gc.setDBid((int)dataReader["ID"]); gymClass.Add(gc); } dataReader.Close(); foreach (GymClass cls in gymClass) { cls.setListCustomerListed(getListedCustomerByClassID(cls.getDBid())); } return gymClass; }