Cancel Purchase Order in x++

// Cancel Purchase Order
--> Open order Purchase order line
-->Partial Product Receipt  line also through x++

private void toCancelPo()
{
    //info(strFmt("%1 -- %2 ",transDate,purchaseOrder));
    Query                   query;
    QueryBuildDataSource    qbds;
    QueryBuildRange         qbrPurchId,qbrDate;
    QueryRun                qr;
    List _list = New List(Types::String);
    ListIterator    lt;
    str 100 PurchNumber;
    ;

    query = new query();
    qbds= query.addDataSource(tableNum(PurchTable));
    qbds.addRange(fieldNum(PurchTable,PurchaseType)).value("Purch");
    qbds.addRange(fieldNum(PurchTable,PurchStatus)).value("Backorder");
    if (transDate != dateNull())
    {
        qbds.addRange(fieldNum(PurchTable,CreatedDateTime)).value(SysQuery::range(fromdate,transDate));
    }
    //info(strFmt("%1 -- %2 -- %3",fromdate,transDate,purchaseOrder));
    //qbds.addRange(fieldNum(PurchTable,OrderAccount)).value("R0003");
    if (purchaseOrder != "")
    {
        _list = Global::strSplit(purchaseOrder,";");
        lt = new ListIterator(_list);
        while(lt.more())
        {
            purchNum += lt.value();
            lt.next();
        }
        for(i = 0; i<= conLen(purchNum);i++)
        {
            PurchNumber = conPeek(purchNum,i);
            qbds.addRange(fieldNum(PurchTable,PurchId)).value(PurchNumber);
        }
    }
    qr = new QueryRun(query);
    while(qr.next())
    {
        purchTable = qr.get(tableNum(PurchTable));
        ttsBegin;
        while select forupdate purchLine
                where purchLine.PurchId == purchTable.PurchId
                    && purchLine.PurchStatus == PurchStatus::Backorder
            join inventTrans
                    join inventTransOrigin
                where inventTransOrigin.RecId         ==  inventTrans.InventTransOrigin
                    && inventTransOrigin.InventTransId == purchLine.InventTransId
        {
                //while select
                //{
                    if(inventTrans.StatusReceipt == StatusReceipt::Ordered)
                    {
                        //purchLine.selectForUpdate(true);
                        purchLine.RemainInventPhysical = 0.00;
                        purchLine.RemainPurchPhysical  = 0.00;
                        purchLine.reread();
                        purchLine.update();
                        InventMovement::bufferSetRemainQty(purchLine);
                    }
               // }
            }
        ttsCommit;
    }
}