should be correct

with t1 as
(SELECT sale_date, product_id,
       SUM(price * Quantity) as Total,
       dense_rank() OVER(PARTITION BY sale_date
       ORDER BY SUM(price * quantity) DESC) as dr
  FROM sales_data
 GROUP BY 1, 2)

SELECT sale_date, product_id, Total
from t1
 WHERE dr = 1
ORDER BY sale_date