Does this small piece of code seem ok?

Hi,

I am not sure why but I am uncomfortable with this piece of code.

All I am doing after this loop is inserting the generated $code value (not for crypotgraphic purposes) into a unique column, in a later query. So to make sure the code is unique I am doing this:

PHP Code:

$loop = TRUE;
 while($loop)
 {
    $code = random_string('alnum', 16);
    $this->db->where('guest_code', $code);
    $check = $this->db->count_all_results('guests');
    if ($check == 0)
    {
       $loop = FALSE;
    }
 } 


But I am uncomfortable with the loop though. Is this a sensible way to do this?

It is working and I have moved on for now but it is bugging me because of the potential for an infinite loop. Is this a bad thing to do or am I being silly.

Any advice would be welcomed,

Best wishes,

Paul.