<?php

    function getPageContent($id)
    {

        global $dbCon;

        $query = 'SELECT pages.title as `title`, pages.visible as `visible`,'
                . ' pages.content as `content`, pages.id as `id`,'
                . ' navPages.id as `pageId`'
                . ' FROM pages'
                . ' JOIN navPages'
                . ' ON navPages.id = pages.id'
                . ' WHERE navPages.id = ' . $id;

        $result = mysql_query($query, $dbCon)or die(mysql_error());

        return $result;

    }

    if(isset($id) && ctype_digit($id))
    {

        $return = getPageContent($id);

    }

    while($row = mysql_fetch_assoc($result))
    {
    i has code here.
    }

?>