9

WITH quantity_sales AS(
    SELECT MAX(quantity) AS max_quantity,
        prod_id
    FROM (
        SELECT prod_id,
            time_id,
            SUM(quantity_sold) AS quantity
        FROM sh.sales
        GROUP BY prod_id, time_id
        ORDER BY quantity DESC, prod_id ASC)
    GROUP BY prod_id
    ORDER BY 1 DESC)
SELECT max_quantity AS "Макс покуп/день",
    prod_name
FROM quantity_sales
JOIN sh.products USING (prod_id)
WHERE rownum <= 20
;