Bestseller aktualisieren

[syncrosoni]

Hallo,

ich möchte realisieren, dass die Bestseller Box immer die meisverkauften Artikel der letzten 30 Tage anzeigt.
Nur leider funktioniert das noch nicht so wie es soll - hab irgendwo nen Denkfehler.
Ich hoffe, es kann mir hier jemand helfen, der etwas mehr Ahnung von Mysql hat als ich.

PHP-Code:

       select blabla
                                        p.products_fsk18,
                                        p.products_id,
                                        p.products_model,
                                        p.products_price,
                                        p.products_tax_class_id,
                                        p.products_image,
                                        pd.products_short_description,
                                        pd.products_name,
                                        o.date_purchased,
                                        o.orders_id,
                                        sum(op.products_quantity) as best_orders from " .
                                        TABLE_PRODUCTS . " p, " .
                                        TABLE_PRODUCTS_DESCRIPTION . " pd, " .
                                        TABLE_PRODUCTS_TO_CATEGORIES . " p2c, " .
                                        TABLE_ORDERS . " o, " .
                                        TABLE_ORDERS_PRODUCTS . " op, " .
                                        TABLE_CATEGORIES . " c
                                        where (date_sub(now(), interval 30 day) > o.date_purchased)
                                        and o.orders_id = op.orders_id
                                        and op.products_id = pd.products_id
                                        and p.products_status = '1'
                                        and c.categories_status = '1'
                                        and p.products_ordered > 0
                                        and p.products_id = pd.products_id
                                        and pd.language_id = '" . (int)$_SESSION['languages_id'] . "'
                                        and p.products_id = p2c.products_id ".$fsk_lock."
                                        ".$group_check."
                                        ".$fsk_lock."
                                        and p2c.categories_id = c.categories_id and '" . $current_category_id . "'
                                        in (c.categories_id, c.parent_id)
                                        group by pd.products_name
                                        order by best_orders desc, pd.products_name limit " . MAX_DISPLAY_BESTSELLERS;