[marcoszorrilla]

Prueba con este código:

Código Delphi [-]
var
  f: TField;
  i: Integer;
begin
 table1.FieldDefs.Update
  Table1.Close;
  for i := 0 to Table1.FieldDefs.Count - 1 do
   {create persistent field that does not exist}
    if table1.FindField(table1.FieldDefs[i].Name) = nil then 
      table1.FieldDefs.Items[i].CreateField(Table1);
    {create a calculated field}
    f := TStringField.Create(Table1);
    f.Name := 'Table1CalcField';
    f.FieldName := 'CalcField';
    f.DisplayLabel := 'CalcField';
    f.Calculated := True;
    f.DataSet := Table1;
   Table1.Open;
end;

Un Saludo.