private void LoadcmbKhachHang()
{
khachHangCtr khctr = new khachHangCtr();
cmbkhachHang.DataSource = khctr.GetData();
cmbkhachHang.DisplayMember = "TenKH";
cmbkhachHang.ValueMember = "MaKH";
cmbkhachHang.SelectedIndex = 0;
}
