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) category_rank
# from (
# select name product_name,category
# ,sum(quantity) total_sales
# from products a
# join orders b
# on a.product_id=b.product_id
# group by product_name,category
# order by category,total_sales desc
# )c

select  a.name product_name,sum(quantity) total_sales,
row_number() over(partition by category order by category, sum(quantity) desc) category_rank
from products a
join orders b
on a.product_id=b.product_id
where quantity is not null
group by a.product_id