tracking hit counter

<?php

// Create a connection to the database
$database = new mysqli('localhost', 'username', 'password', 'databasename') or die('Could not connect to database');

// Ensure that the user input is available and safe
if (!isset($_REQUEST['file'])) die('no file id provided');

$file = $_REQUEST['file'];
if (preg_match("/[^0-9]/", $file))        die('bad file');

$ip = $_SERVER['REMOTE_ADDR'];
if (preg_match("/[^a-fA-F0-9\.:]/", $ip)) die('bad ip');

// Add this visitor to the list
$database->query("insert into ipcounter values(0, '$file', '$ip', now())") or init();

// Do a mysql "search" to get the hitcounter
$result = $database->query("select count(distinct ip) hits from ipcounter where file = '$file'") or die('error selecting hit count');

// Read the result
if ($result = $result->fetch_assoc())
{
    // Show the hitcount
    echo $result['hits'];
}
else init();



// This will create the required table if something goes fuck
function init()
{
    global $database;

    echo 'Re-initializing database due to error: ' . $database->error;

    $database->query('drop table if exists ipcounter') or die('could not delete table: ' . $database->error);
    $q = <<<Q
create table if not exists ipcounter (
    id int(11) not null auto_increment,
    file int(11) not null,
    ip varchar(45) not null,
    time timestamp not null default current_timestamp,
    primary key (id),
    key (ip))
Q;
    $database->query($q) or die('could not create table: ' . $database->error);
}