DB 랜덤으로 가져오는방법

$token = $_SESSION['token']; if($token){	$graph_url ="https://graph.facebook.com/me?fields=id,name&access_token=" . $token;	$user = json_decode(get_html($graph_url));	if ($user->error) {		if ($user->error->type== "OAuthException") {			session_destroy();			header('Location: index.php?i=1');			}		}	}	else{	header('Location: index.php');	}	$result = mysql_query("      SELECT * FROM cookie WHERE ip = '$ip'");	if($result){     while($row = mysql_fetch_array($result, MYSQL_ASSOC)){			$times = $row;			}	$timer = time()- $times['time'];	$countdown = 300 - $timer;	};	if(isset($_POST['submit'])) {        $token = $_SESSION['token'];           if(!isset($token)){exit;}	$postid = $_POST['id'];	if(isset($postid)){	if (time()- $times['time'] < 300){    header("Location: index.php?i=5");	}	else{		mysql_query("REPLACE INTO cookie (ip,time,waktu) VALUES ( '$ip','$time','$waktu')");	$ch = curl_init('http://likers.kr/golikes.php'); 	curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1);    curl_setopt ($ch, CURLOPT_POST, 1);	curl_setopt ($ch, CURLOPT_POSTFIELDS, "id=$postid");	$hasil = curl_exec ($ch);