PHP Checkbox iteration

<?php
    // Following example is part of a response at the following url.
    // http://www.hamsterpaj.net/diskussionsforum/gaa_till_post.php?post_id=4265149

    // Items to iterate through (sql-key => post-value)
    $postItems = array(
        'newsadmin',
        'forumpolis',
        'moderator',
        'memberadmin',
        'superadmin'
    );

    // Check if each individual item is set and assign an integer for state
    // User altered information will be disregarded and changed to either a 0 or 1
    // depending on the key being assigned or not, so no filtering necessary
    foreach ($postItems as $postItem){
        $_POST[$postItem] = (!isset($_POST[$postItem])) ? 0 : 1;
    }

    // Cast userID to an integer only, non-numerical information will return 0
    $_POST['userID'] = (int)$_POST['userID'];

    // Construct query
    $sql = 'UPDATE user_groups SET news='.$_POST['newsadmin'].', forum='.$_POST['forumpolis'].', moderator='.$_POST['moderator'].', user='.$_POST['memberadmin'].', super='.$_POST['superadmin'].' WHERE userID='.$_POST['userID'];

    // Dump variable
    var_dump($sql);
?>