private void LoadCourses()
        {
            Online_Exame exam   = new Online_Exame();
            var          std    = (from s in exam.Students where s.St_id == stdID select s).First();
            var          course = exam.getCoursesByDeptID(std.Dept_id).ToList();


            foreach (var item in course)
            {
                string cour = item.C_id + "," + item.C_name;
                listBox1.Items.Add(cour);
            }
        }
        private void LoadCourses()
        {
            Online_Exame exam   = new Online_Exame();
            var          std    = (from s in exam.Instractors where s.Ins_id == inst select s).First();
            var          course = exam.getCoursesByDeptID(std.Dept_id).ToList();


            foreach (var item in course)
            {
                string cour = item.C_id + "," + item.C_name;
                comboBox1.Items.Add(cour);
            }
        }