private void BillingEngine_BeforeSave(object sender, MercatorUi.Engine.Gescom.BillingEngine.BeforeSaveEventArgs e)
{
    MercatorUi.Engine.Gescom.BillingEngine billingEngine = (MercatorUi.Engine.Gescom.BillingEngine)sender;
    DataTable dtArticles = new DataTable();
    dtArticles.Columns.Add("s_id", typeof(string));
    foreach(DataRow dr in billingEngine.LIGNES.Select("id_article<>''"))
        dtArticles.Rows.Add(new object[1] { dr["id_article"] });
    using (MercatorSqlConnection conn = new MercatorSqlConnection(MercatorUi.Globals.RepData, true))
    {
        if (!conn.IsConnected)
        {
            e.CancelSave = true;  // connectie geweigerd door de SQL-server -> we stoppen het bewaren
            return;
        }
        if (!Api.BulkDataTable(dtArticles, "#art_tmp", conn.Connection, null, "STOCK"))
        {
            e.CancelSave = true; //error tijdens de bulk van de DataTable -> we stoppen het bewaren
            return;
        }

        using (MercatorSqlCommand cmd = new MercatorSqlCommand("", conn))
        {
            cmd.CommandText = "select s_id,s_xxx,s_yyy from STOCK inner join #art_tmp on (stock.s_id=#art_tmp.s_id) \r\n"
                            + "drop table #art_tmp";
            DataSet ds = Api.Zselect(cmd);
            if (ds == null)
            {
                e.CancelSave = true;  // de query hierboven geeft een fout -> we stoppen het bewaren
                return;
            }
            Api.TrimEndDataTable(ds.Tables[0]);

            foreach (DataRow dr in billingEngine.LIGNES.Select("id_article<>''"))
            {
                DataRow[] foundRows = ds.Tables[0].Select(string.Format("s_id='{0}'", Api.UnquoteSql(dr["id_article")))):
                if (foundRows.Length > 0) // zal altijd het geval zijn, wanneer alle artikelen bestaan    

                {
                    dr["xxx"] = foundRows[0]["s_xxx"];
                    dr["yyy"] = foundRows[0]["s_yyy"];
                }
            }
        }
    }
}