Simple lookup Through X++

 public void lookup(FormControl _formControl, str _filterStr)

{
    //super(_formControl, _filterStr);
    QueryBuildDataSource qbd;

    SysTableLookup sysTableLookup = sysTableLookup::newParameters(tableNum(InventTable), _formControl);

    Query  query= new Query();
    qbd = query.addDataSource(tableNum(InventTable));
    sysTableLookup.addLookupfield(fieldNum(InventTable, ItemId));
    sysTableLookup.addLookupfield(fieldNum(InventTable, NameAlias));
    sysTableLookup.parmQuery();
    sysTableLookup.performFormLookup();
}