private void delete_button_Click(object sender, EventArgs e)
 {
     try
     {
         int       a  = int.Parse(dtg_hoadon.CurrentRow.Cells[0].Value.ToString());
         DAOHoaDon hd = new DAOHoaDon();
         hd.xoahoadon(a);
         DataTable tb = new DataTable();
         tb = hd.getHoaDon();
         dtg_hoadon.DataSource = tb;
     }
     catch (Exception lo)
     {
         MessageBox.Show(lo.Message);
     }
 }
        private void frmdanhsachdonhang_Load(object sender, EventArgs e)
        {
            if (Globals.role == "employee")
            {
                delete_button.Visible = false;
            }


            try
            {
                DAOHoaDon hd = new DAOHoaDon();
                DataTable tb = new DataTable();
                tb = hd.getHoaDon();
                dtg_hoadon.DataSource = tb;
            }
            catch
            {
            }
        }