Feature TMyCommand

[jkuiper]

Is it possible to make a feature on TMyCommand to give a good errormessage. Now you can check only on rowsaffected. If it is -1, it tells the insert / update /delete has failed. It's easier go get the right databaseerror to see what's rely going on. An onError event should also be nice.

I know I can use TMyQuery. But as far as I know Devart alswas tell to use TMyCommand, because it's mutch faster.

[Dimon]

On arising of error TMyCommand should raise the same error that TMyQuery.
Please try to compose a small sample to demonstrate the problem and send it to dmitryg*devart*com.

[john_kuiper]

Sorry for the very late reply

Code: Select all

procedure TDMFactwizard.ClearFust(const snr : integer);
var MyCMD  : TMyCommand;
begin
  MyCMD   := TMyCommand.Create(nil);
  try
    MyCMD.Connection := dmalg.MyConnection1;
    MyCMD.SQL.Text := 'DELETE FROM fustadminverkoop WHERE verkooporderID = :snr';
    MyCMD.Params[0].Value := snr;
    MyCMD.Execute;
    if MyCMD.RowsAffected = -1 then
      showmessage('error deleting fustadminverkoop');
  finally
    MyCMD.Free;
  end;
end;

It is not telling why the delete does not work. TMyCommand does not have de event OnPostError.

[DemetrionQ]

Hello.

If no record is deleted, then MyCMD.RowsAffected = 0. This is not an error: there just was no such records in the table when query was executed. If, on execution of the query (the MyCMD.Execute), an SQL Error occurs (for example, you have specified a nonexistent table or field), and you need to retrieve the information about this error, you can use one of the following ways:

use the "on e: Exception do" instruction, for example:

Code: Select all

  try
    MyCMD.SQL.Text := 'DELETE FROM fustadminverkoop WHERE verkooporderID = :snr';
    MyCMD.Params[0].Value := snr;
    MyCMD.Execute;
  except
    on e: Exception do begin
      ShowMessage('Error :' + e.Message);
    end;
  end;

use the OnError event of the TMyConnection component, for example:

Code: Select all

procedure TForm1.MyConnection1Error(Sender: TObject; E: EDAError;
  var Fail: Boolean);
begin
  ShowMessage('Error :' + E.Message);
  Fail :=  False; //in order for the system error message not to appear
end;