How to find the percentage of a single product of a supplier's total revenue?

Question

There are multiple suppliers and each has sold multiple products. How would I find the percentage of the revenue of one of their products against that supplier's total sales in SQL?

Here is an example of data I have to work with:

supplier	product	price of product	quantity sold
Supplier A	Apples	$2	1
Supplier A	Shoes	$3	2
Supplier B	Shirts	$1	3

The revenue of Supplier A's apples should be $2, their total revenue is $8. So the percentage of Supplier A's apples against total sales should be 25%.

Answer 1

You would use divide values . . . and use window functions:

select supplier, product, sum(price * quantity),
       sum(price * quantity) / sum(sum(price * quantity)) over (partition by supplier) as ratio
from t
group by supplier, product;