Lookup for Product varients

public void lookup()
{
    Query                  query ;
    QueryBuildDataSource   qbdsInventdim,qbdsInventDimCombination;
    QueryBuildRange        qbr;
    SysTableLookup         sysTableLookup;


    sysTableLookup  = sysTableLookup::newParameters(tableNum(InventDim),this);
    sysTableLookup.addLookupfield(fieldNum(InventDim,InventSizeId));

    query           = new Query();
    qbdsInventdim    = query.addDataSource(tableNum(InventDim));
    qbdsInventDimCombination = qbdsInventdim.addDataSource(tableNum(InventDimCombination));
    qbdsInventDimCombination.addLink(fieldNum(inventDim,InventDimId),fieldnum(InventDimCombination,InventDimId));
    qbr = qbdsInventDimCombination.addRange(fieldNum(inventDim,InventDimId));
    qbr.value(CICInternalRequisitionTable_Product.valueStr());


    sysTableLookup.parmQuery(query);
    sysTableLookup.performFormLookup();
}