Delphi & Oracle

  
var
  i: Integer;
begin
  i := Field.AsInteger;  <-- 정상적으로 1이 rerutn된다.
end;

  
var
  i: Integer;
begin
  i := Field.AsInteger; <-- 에러를 발생하게 된다.
end;

  
if Field.IsNull then
  i := 0
else
  i := Field.AsInteger;
or
i := StrToIntDef(Field.AsString, 0);

  
TStringField = class(Data.DB.TStringField)
protected
  function GetAsInteger: LongInt; override;
end;

function TStringField.GetAsInteger: LongInt;
begin
  Result := StrToIntDef(AsString, 0);
end;

or

function TStringField.GetAsInteger: LongInt;
begin
  if AsString = '' then
    Result := 0
else
    Result := inherited(AsInteger);
end;

  
TMyStringField = class(Data.DB.TStringField)
protected
  function GetAsInteger: LongInt; override;
end;

function TMyStringField.GetAsInteger: LongInt;
begin
  if AsString = '' then
    Result := 0
else
    Result := inherited(AsInteger);
end;

initialization
  RegisterClass(TMyStringField);
  DefaultFieldClasses[ftString] := TMyStringField;
finalization
  UnRegisterClass(TMyStringField);

  
try
except
  on e: exception do
    Application.OnException(self, e);  // into TApplicatoinEvent.OnException event

  
FDDataSet.FilterChange := [rtModified, rtInserted, rtDeleted];

  
var
  oJournal: TFDDatSUpdatesJournal;
  oRow: TFDDatSRow;
begin
  oJournal := FDDataSet.Delta.DataView.Manager.Updates;
  if oJournal = nil then
    Exit;

  oRow := oJournal.FirstChange;
  while oRow <> nil then
  begin
    // To Do
    oRow := oJournal.NextChange(oRow);
  end;
end; 

- Data는 GetValue, GetData를 사용

  oRow.GetData("Column Name or Column Index", TFDDatSRowVersion)

  [TFDDatSRowVersion]

  rvOriginal: 원본 (OldValue)

  rvDefault: 현재값(NewValue)