WITH
RankedSpending AS (
SELECT
Sales.user_id,
Sales.product_id,
RANK() OVER(
PARTITION by user_id
ORDER BY SUM(Sales.quantity * Product.price) DESC
) AS `rank`
FROM Sales
INNER JOIN Product
USING (product_id)
GROUP BY 1, 2
)
SELECT user_id, product_id
FROM RankedSpending
WHERE `rank` = 1;
¶
