Well, it depends on what you do, actually. I understand that he prints his 'DB' with print @guests. In that case, you need to separate the fields with $,. The $\ is active after each print statement, as appears from:

$OUTPUT_FIELD_SEPARATOR
$OFS
$,
The output field separator for the print operator. Ordinarily the print operator simply prints out its arguments without further adornment. To get behavior more like awk, set this variable as you would set awk's OFS variable to specify what is printed between fields. (Mnemonic: what is printed when there is a "," in your print statement.)

$OUTPUT_RECORD_SEPARATOR
$ORS
$\
The output record separator for the print operator. Ordinarily the print operator simply prints out its arguments as is, with no trailing newline or other end-of-record string added. To get behavior more like awk, set this variable as you would set awk's ORS variable to specify what is printed at the end of the print. (Mnemonic: you set `$\' instead of adding "\n" at the end of the print. Also, it's just like `$/', but it's what you get "back" from Perl.)

So it makes no sense to set $, and $\ to the same value.

Jeroen