partial void DeleteDonHang(DonHang instance);
 partial void UpdateDonHang(DonHang instance);
 private void detach_DonHangs(DonHang entity)
 {
     this.SendPropertyChanging();
     entity.KhachHang = null;
 }
 partial void InsertDonHang(DonHang instance);
 private void attach_DonHangs(DonHang entity)
 {
     this.SendPropertyChanging();
     entity.KhachHang = this;
 }