# fetching keys and values
  @keys = keys %h;
  @fields = keys %{$h{$keys[0]}};
  print $h{'id1'}->{'field1'};
  while (($key,$value) = each %h) {
    print "Key = $key:\n";
    foreach (sort keys %$value) {
        print "\t$_ => $value->{$_}\n";
    }
  }

  # changing data
  $h{'id1'}->{'field1'} = 'new value';
  $h{'id1'} = { field1 => 'newer value',
                field2 => 'even newer value',
                field3 => "so new it's squeaky clean" };