| select product_class.product_family as c0, product_class.product_department as c1, product_class.product_category as c2, product_class.product_subcategory as c3 from product as product, product_class as product_class where product.product_class_id = product_class.product_class_id group by product_class.product_family, product_class.product_department, product_class.product_category, product_class.product_subcategory order by product_class.product_family ASC NULLS LAST, product_class.product_department ASC NULLS LAST, product_class.product_category ASC NULLS LAST, product_class.product_subcategory ASC NULLS LAST; |