[titov]

static void PurchLineQuery(Args _args)
{
    QueryBuildDataSource        qbdsPurchLineSum,qbdsPurchTable,qbds;
    QueryBuildRange             qbr;
    Query                       q = new Query();
    QueryRun                    qr;
    PurchLine                   PurchLine;
    #define.itemIdParm('123')
    ;
    qbdsPurchLineSum    = q.addDataSource(tableNum(PurchLine));
    qbdsPurchLineSum.addSelectionField(fieldNum(PurchLine,PurchQty),SelectionField::Sum);//внимание на единицы измерения! может даже лучше идти по inventTrans
    qbr                 = sysQuery::findOrCreateRange(qbdsPurchLineSum,fieldNum(PurchLine,PurchStatus));
    qbr.value(queryValue(PurchStatus::Backorder));
    qbr                 = sysQuery::findOrCreateRange(qbdsPurchLineSum,fieldNum(PurchLine,ItemId));
    qbr.value(queryValue(#itemIdParm));

    qbdsPurchTable      = qbdsPurchLineSum.addDataSource(tableNum(PurchTable));
    qbdsPurchTable.joinMode(joinMode::ExistsJoin);
    qbdsPurchTable.fetchMode(QueryFetchMode::One2One);
    qbdsPurchTable.relations(true);
    qbr                 = sysQuery::findOrCreateRange(qbdsPurchTable,fieldNum(PurchTable,PurchStatus));
    qbr.value(queryValue(PurchStatus::Backorder));
    qbds                = qbdsPurchTable.addDataSource(tableNum(PurchLine));
    qbds.joinMode(joinMode::NoExistsJoin);
    qbds.fetchMode(QueryFetchMode::One2One);
    qbds.relations(true);
    qbr                 = sysQuery::findOrCreateRange(qbds,fieldNum(PurchLine,ItemId));
    qbr.value(queryValue(#itemIdParm));
    qbr                 = sysQuery::findOrCreateRange(qbds,fieldNum(PurchLine,RecId));
    qbr.value(strFmt('((%1.%2 != "%3") || (%4.%5 == "%5"))',
                        qbds.name(),
                        fieldId2name(tableNum(PurchLine),fieldNum(PurchLine,PurchStatus)),
                        queryValue(PurchStatus::Backorder),
                        qbds.name(),
                        fieldId2name(tableNum(PurchLine),fieldNum(PurchLine,Blocked)),
                        queryValue(NoYes::Yes)
                     )
             )       ;
    info(qbdsPurchLineSum.toString());
    qr              = new QueryRun(q);
    while (qr.next())
    {
        PurchLine       = qr.get(PurchLine.TableId);
        info(strFmt("%1 %2",PurchLine.PurchId,PurchLine.PurchQty));
    }
}

примерно так (4.0 в т.ч.)