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        private void cmd_ermitteln_Click(object sender, EventArgs e)
        {
            string s_artikel = inp_nr.Text;
            string SQL1 = "Select * from A";
            string SQL2 = "Select * from B";
            SqlCommand cmd = new SqlCommand(SQL1, con);
            SqlCommand cmd1 = new SqlCommand(SQL2, con);
            SqlDataReader reader1, reader2; 
              
            con.Open();
                reader1 = cmd.ExecuteReader(); 
                while (reader1.Read())
                {
                    inp_bestand1.Text = reader1["MENGE1"].ToString();
                    inp_bestand2.Text = reader1["MENGE2"].ToString();
                }
                reader1.Close();

                reader2 = cmd1.ExecuteReader();
                while (reader2.Read())
                {
                    inp_artikelbeschreibung.Text = reader2["Beschreibung"].ToString() + " " + reader2["Beschreibung 2"].ToString();
                }
                reader2.Close();
            con.Close();
        }					

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reader2 = cmd1.ExecuteReader();					

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select A.Nr_, A.Beschreibung, A.[Beschreibung 2], A.Kreditorennr_, A.[Kred_-Artikelnr_], K.Name, E.Name, E.Telefon 
from [Artikel] A, [Kreditor] K, [Verkäufer_Einkäufer] E 
where A.Nr_ = '341'
and k.Nr_ = a.Kreditorennr_
and K.Einkäufercode = E.Code