题解 | 每个商品的销售总额

SELECT
    p_1.name product_name,
    total_sales,
    ROW_NUMBER() OVER(PARTITION BY p_1.category ORDER BY p_1.category,total_sales DESC,p_1.product_id ) category_rank
FROM 
    (SELECT 
        p.product_id,
        SUM(o.quantity) total_sales
    FROM orders o
    JOIN products p ON p.product_id = o.product_id
    GROUP BY p.product_id) t_1
JOIN products p_1 ON p_1.product_id = t_1.product_id