Query value to textbox c#

Question

I have result System.Data.SqlClient.SqlDataReader

Some help?

private void ukupno_bez_pdv_roba()
{
    SqlConnection con2 = new SqlConnection(cs);
       string sqlquery = ("select * from mp_racun_roba where tip_robe = 'Roba (Generalno)' and id=" + id_fakture);
    SqlCommand command = new SqlCommand(sqlquery, con2);
    con2.Open();
    SqlDataReader sdr = command.ExecuteReader();

    roba_bez_pdvTextBox.Text = sdr.ToString();
    con2.Close();
}