Read Only TQuery objects?

["Mark Hanna" <mlhanna@arn.net>]

Hello All,

 

    I am creating a TQuery and using the SQL property to specify a dataset.  Whenever I get around to editing fields in the dataset I use the following commands and receive the folloing error: "Cannot modify read-only dataset".  Does anyone know how to modify a TQuery dataset?

 

code:

 

TQuery *TrackPos = new TQuery(frmMain);
        AnsiString TrackToUpdate =  TableCar->FieldByName("TrackNum")->AsString;
        int OldPosition = TableCar->FieldByName("Position")->AsInteger;
        TrackPos->DatabaseName = "c:\\cardata";
        TrackPos->SQL->Clear();
        TrackPos->SQL->Add("SELECT * FROM railcars WHERE  TrackNum=""+TrackToUpdate+"\"");
        TrackPos->Open();
  do {
   if(TrackPos->FieldByName("Position")->AsInteger>OldPosition) { 

               

              TrackPos->Edit();  //Line giving error
                TrackPos->FieldByName("Position")->AsInteger = TrackPos->FieldByName("Position")->AsInteger - 1;
                TrackPos->Post();
            }
            TrackPos->Next();
        } while(!TrackPos->Eof);