Rename Wordpress Database Prefix

PHP: Rename WordPress prefix

<?php
function changePrefixWP ($old_pref,$new_pref,$server,$user,$pass,$bd) {
	//Connect with DB
	$link =  mysql_connect($server, $user, $pass);
	if (!$link) {
	    die('Error: ' . mysql_error());
	}
	//Get the table resource
	$result = mysql_list_tables($bd);

	//Count the number of tables
	$num_rows = mysql_num_rows($result);
	//Rename all the tables name
	for ($i = 0; $i < $num_rows; $i++) {
		//Get name old table name
		$table_old_name = mysql_tablename($result, $i);
		//Set name new table name
		$table_new_name = $new_pref . substr($table_old_name, strlen($old_pref));
		$sql = "RENAME TABLE $table_old_name TO $table_new_name";
		if (mysql_query($sql)) {
			echo "ok: ".$sql."<br>";
		}else {
			echo "error: ".$sql."<br>";
		}
	}
	
	//Fix other tables
	//Select Database
	if (!mysql_select_db($bd)) {
    	echo "No Database Selected: " . mysql_error();
    	exit;
	}
	//wp_options
	$sql = 'UPDATE '.$new_pref.'options SET option_name="'.$new_pref.'user_roles" WHERE option_name LIKE "'.$old_pref.'user_roles"';
	if (mysql_query($sql)) {
		echo "ok: ".$sql."<br>";
	}else {
		echo "error: ".$sql."<br>";
	}
	//wp_usermeta
	$sql = 'SELECT * FROM '.$new_pref.'usermeta WHERE meta_key LIKE "'.$old_pref.'%"';
	$result = mysql_query($sql,$link) or die("Error en: $sql: " . mysql_error());
	while ($row = mysql_fetch_array($result)) {
	    $sql = 'UPDATE '.$new_pref.'usermeta SET meta_key="'.$new_pref.substr($row['meta_key'], strlen($old_pref)).'" WHERE meta_key LIKE "'.$old_pref.substr($row['meta_key'], strlen($old_pref)).'"';
	    //echo $sql."<br>";
	    if (mysql_query($sql)) {
			echo "ok: ".$sql."<br>";
		}else {
			echo "error: ".$sql."<br>";
		}
	}	
	//Close connection
	mysql_close($link);
}

$old_prefix = 'pru_';
$new_prefix = 'lib_';
$server = 'localhost';
$user = 'root';
$pass = 'root';
$bd = 'libelium_alpha';

changePrefixWP($old_prefix,$new_prefix,$server,$user,$pass,$bd);

echo "The End...";

?>