how to generate shortest possible string in php? [duplicate]

This question already has answers here: 开发者_如何学C Closed 12 years ago.

Possible Duplicate:

How to code a URL shortener?

How to generate shortest possible string (the way e.g. bit.ly is doing this)?

---

Well you would have to make random string and then check if you allredy have it in your database! Here i write you a example how to. Btw. this is just a quick one. There are much more things that could be checked to speed it up!

$cl=2;
$cr=0;
$n="";
while(!$e){
  if($cr>500){$cr=0;$cl++;}
  $n=genRandomString($cl);
  $checker = mysql_query("select count(*) as haveit from table where thestring='".$n."'");
  $xa = mysql_fetch_array($checker);
  if($xa['haveit']==0){$e=1;}
  $cr++;
}

function genRandomString($len){
    $length = $len;
    $characters = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    $string = '';
    for ($p = 0; $p < $length; $p++) {
        $string .= $characters[mt_rand(0, strlen($characters))];
    }
    return $string;
}

This is just to give you idea how to do it! This have to be optimized a little! :D