You know you always have access to the specific date, right? Well, using the date function, you can obtain all manner of amusing and fun information. If you just need a daily unique id, you could even use the date itself:
$id_st = date("Ymd");
But lets say you don't want it to be obvious that you're using the date. Perhaps you need to conceal this fact from the casual observer because you don't want them looking at upcoming updates or something. You could use something like this:
$id_st = date("Ymd"); // for today, this would return "20010910";
$id_st = ($id_st-2016124)*date("d");
Now $id_st is set to 179947860
Tomorrow it will be: 197942646
Not the best example, perhaps, but you get the idea.
