Get Mainaccount lookup thorugh lookup code

 Query query = new query();

   QueryBuildDataSource qbds; 
   QueryBuildRange qbr;
   SysTableLookup  sysTableLookup;
   sysTableLookup= SysTableLookup:: newParameters (tableNum (MainAccount),this);
   sysTableLookup.addLookupfield (fieldNum (MainAccount, MainAccountId));
   sysTableLookup.addLookupfield (fieldNum (MainAccount, Name));
   qbds = query.addDataSource(tableNum (MainAccount));
   qbds.orderMode(OrderMode::GroupBy);
   qbds.addGroupByField(fieldNum(MainAccount, MainAccountId));
   qbds.addGroupByField(fieldNum(MainAccount, Name));
   //qbr = qbds.addRange(fieldNum (MainAccount, LedgerChartOfAccounts)); 
   //qbr.value(queryValue (LedgerChartOfAccounts::current()));
   sysTableLookup.parmQuery(query); 
   sysTableLookup.performFormLookup();