public Supervisor_Form()
        {
            Business_Layer.CLS_Add_Student sup = new Business_Layer.CLS_Add_Student();

            InitializeComponent();

            da = new SqlDataAdapter("SELECT ID AS 'ID',FIRST_NAME AS 'First Name',LAST_NAME AS 'Last Name',PHONE_NUMBER AS 'Phone Number',MAIL AS 'Mail',CITY AS 'City',SALARY AS 'Salary',HIRE_DATE AS 'Hire Date',ClASS AS 'Class Name' from SUPERVISOR", sqlcon);

            da.Fill(dt);

            metroGrid1.DataSource = dt;

            txtboxID.DataBindings.Add("text", dt, "ID");
            txtboxFirstName.DataBindings.Add("text", dt, "First Name");
            txtboxLastName.DataBindings.Add("text", dt, "Last Name");
            txtboxPhoneNumber.DataBindings.Add("text", dt, "Phone Number");
            txtboxEmail.DataBindings.Add("text", dt, "Mail");
            txtboxCity.DataBindings.Add("text", dt, "City");
            txtboxSalary.DataBindings.Add("text", dt, "Salary");
            txtboxHireDate.DataBindings.Add("text", dt, "Hire Date");
            txtboxClass.DataBindings.Add("text", dt, "Class Name");

            bmb = this.BindingContext[dt];
            lebPosition.Text = (bmb.Position + 1) + " / " + bmb.Count;


            txtboxClass.DataSource    = sup.Get_All_Class();
            txtboxClass.DisplayMember = "Get_All_Class";
            txtboxClass.ValueMember   = "CLASS_NAME";
        }