Improve My SQL

I have the following SQL, which works but I think it can be done simplier. I seem to have to group it by multiple columns, but I am sure there must be a way of grouping the results by a single column. Any Ideas?

Code:


SELECT count(order_items.order_id) as treenum, orders.order_id, orders.order_date,
orders.cust_order, orders.del_date, orders.confirmed, orders.del_addr
FROM orders, order_items
WHERE orders.order_id = order_items.order_id GROUP by orders.order_id, orders.order_date
, orders.cust_order, orders.del_date, orders.confirmed, orders.del_addr
ORDER BY orders.order_id DESC