private void txtTimKiem_TextChanged(object sender, TextChangedEventArgs e) { string tenDv = txtTimKiem.Text; if (tenDv.Equals("")) { dgDanhSach.ItemsSource = DichVuDAO.LoadConSuDung().DefaultView; } else { dgDanhSach.ItemsSource = DichVuDAO.TimTheoTen(tenDv).DefaultView; } }