private void btnAdd_Click(object sender, EventArgs e)
        {
            StudentAddForm frm = new StudentAddForm(this);

            frm.id = 0;
            frm.ShowDialog();
        }
 private void btnModify_Click(object sender, EventArgs e)
 {
     if (flx.Rows.Count > 1)
     {
         StudentAddForm frm = new StudentAddForm(this);
         frm.id = Convert.ToInt32(flx[flx.RowSel, "id"]);
         frm.ShowDialog();
     }
     else
     {
         Box.warnBox("Please select data.");
     }
 }