try:
cmd.CommandText = ("SELECT itemcode,maturity FROM SAUDAMAST WHERE COMPCODE=@COMPCODE and itemcode=@itemcode and maturity=@maturity");
cmd.Parameters.AddWithValue("@COMPCODE", Compcls.Gcomp_cd);
cmd.Parameters.AddWithValue("@itemcode", comboBox1.SelectedValue);
cmd.Parameters.AddWithValue("@maturity", date1);