// load in variables from a mysql db and assign them to the template
require_once("MySQL.class.php");
$sql = new MySQL;
$sql->query("select * from site_nav_sections order by name",SQL_ALL);
$this->assign('sections',$sql->record);
?>
index.tpl
---------
{* absolute path, or relative to $trusted_dir *}
{include_php file="/path/to/load_nav.php"}