private void LoaData()
{
TourBUS tourBus = new TourBUS();
dgv_Tour.DataSource = tourBus.LoadTourToDataGridView();
DataTable diaDiem = tourBus.LoadDiaDiem();
cbo_NoiDi.DisplayMember = "TenDiaDiem";
cbo_NoiDi.ValueMember = "MaDiaDiem";
cbo_NoiDi.DataSource = diaDiem;
cbo_NoiDen.DisplayMember = "TenDiaDiem";
cbo_NoiDen.ValueMember = "MaDiaDiem";
cbo_NoiDen.DataSource = tourBus.LoadDiemDen(int.Parse(cbo_NoiDi.SelectedValue.ToString()));
}