q3

SELECT category.name AS category_name, sum(good.price) AS profit
FROM category
LEFT JOIN category_has_good
ON category.id = category_has_good.category_id
LEFT JOIN good
ON good.id = category_has_good.good_id
LEFT JOIN sale_has_good
ON sale_has_good.good_id = good.id
LEFT JOIN sale
ON sale_has_good.sale_id = sale.id
GROUP BY category_name
ORDER BY category_name
LIMIT 5;