题解 | #每个商品的销售总额#

select name product_name,total_sales,category_rank
from(
select name,sum(quantity) total_sales,row_number() over(partition by category order by sum(quantity) desc,t1.product_id) category_rank
from products t1 join orders t2 on t1.product_id=t2.product_id
group by name,category,t1.product_id#group by 创建分组：注1:不能使用别名，原因可以去了解SQL的运行逻辑；注2:除聚集计算语句外，select语句中的每一列都必须在group by 子句中给出
order by category,sum(quantity) desc) t;