The SQL doesn't seem quite right, but you can access the field(s) by name. For example:
Code
OracleDataSet1->Close();
OracleDataSet1->SQL->Clear();
OracleDataSet1->SQL->Add(SQL);
OracleDataSet1->Open();
if (!OracleDataSet1->Eof) 
  ShowMessage(OracleDataSet1->FieldByName("feature_id")->AsString);

Marco Kalter
Allround Automations