var
  dbf :integer;
  r :integer;
begin
  dbf := OpenBase( 'filename.dbf' );
  if dbf <> 0 then
  begin
    for r := 0 to RecCount(dbf)-1 do
    begin
      ReadRecord(dbf, r);
       // some actions
      WriteRecord(dbf, r);
    end;
    CloseBase(dbf);
  end;
end.