procedure ...DataSetBeforeOpen(DataSet: TDataSet);
var
  Index: Integer;
  Field: TField;
begin
  if DataSet.Fields.Count <>  0  then Exit;
  DataSet.FieldDefs.Update;
  for Index :=  0  to DataSet.FieldDefs.Count -  1  do
    DataSet.FieldDefs[Index].CreateField(DataSet);
  Field := TStringField.Create(DataSet);
  Field.Calculated := True;
  Field.FieldName := 'YesNo';
  Field.Size :=  3 ;
  Field.DataSet := DataSet;
end;

procedure ...DataSetCalcFields(DataSet: TDataSet);
var
  Field: TField;
begin
  Field := DataSet.FindField('YesNo');
  if not Assigned(Field) then Exit;
  if DataSet.FieldByName('YesNoBinary').AsInteger =  1 
    Field.AsString := 'Нет'
  else
    Field.AsString := 'Да';
end;