public void set_Emp_Id(int id)
        {
            this.E_Id = id;
            string RoomNo = emp.ret_Emp_Room(id);

            textBox1.Text = RoomNo;
            List <int> rooms = emp.Ret_Empty_Room();

            foreach (int room in rooms)
            {
                comboBox1.Items.Add(room.ToString());
            }
        }