A Unique Alphanumeric String with for an identification value.

unique.php

// https://codebriefly.com/unique-alphanumeric-string-php/

function unique_code($id, $limit)
{
  $randomId = $id . mt_rand();
  return substr(base_convert(sha1(uniqid($randomId)), 16, 36), 0, $limit);
}