I'm non experienced in SQL, so I need help

I got the following sql-query within public function getOrder($order_id):
Code: Select all
$order_query = $this->db->query("SELECT *, (SELECT os.name FROM `" . DB_PREFIX . "order_status` os WHERE os.order_status_id = o.order_status_id AND os.language_id = o.language_id) AS order_status FROM `" . DB_PREFIX . "order` o WHERE o.order_id = '" . (int)$order_id . "'");
additionally I need the corresponding tax_rate_id to get the tax_rate_name, which I want to display in catalog\view\theme\kitro\template\mail\order.tpl (email which is sent right after checkout).
Hope someone can help me to "upgrade" the sql query

Thank you very much
Andreas