The finance team wants to include product categories in its order-level reporting.
The order_items table contains individual order lines, while the products table stores product details, including their categories.
Prepare a report showing the category associated with every order line. Some order lines may have missing product IDs or reference products that do not exist in the products table.
All order lines must remain in the report, even when product information is unavailable. In such cases, use 'uncategorized' as the category.
Each original order line should appear exactly once.
Ordering: Sort by order_id, then product_id, both in ascending order.