题解 | 每个商品的销售总额

select
product_name,
total_sales,
row_number()over(partition by category order by total_sales desc,product_id) as category_rank
from(
select
orders.product_id,
sum(quantity) as total_sales,
category,
name as product_name
from orders join products on orders.product_id =  products.product_id
group by orders.product_id, products.category, products.name
) tmp

注意：

1 非聚合列都必须出现在 GROUP BY 子句中，select只能两种groupby字段和聚合