题解 | #每个商品的销售总额#

select bb.name as product_name,bb.sq as total_sales,rank()over(partition by cc.category order by bb.sq desc,bb.product_id asc) as category_rank from 
(select name,product_id,sum(quantity) sq from 
(select a.product_id,a.name,a.category,b.quantity
from products a
join orders b
on a.product_id=b.product_id)aa
group by name,product_id
ORDER BY category, sq DESC)bb
join products cc
on  bb.product_id=cc.product_id