Roman K

DELIMITER $$
CREATE TRIGGER `items_BEFORE_INSERT` BEFORE INSERT ON `items` FOR EACH ROW
BEGIN
	DECLARE oldmax INT;
	SELECT IFNULL(MAX(`alt_id`), 0) 
		FROM `items` 
		WHERE `category_id` = NEW.`category_id` 
        INTO oldmax;
	SET NEW.`alt_id` = oldmax+1;
END$$
DELIMITER ;

A = ['1.01', '2.01', '3.01', '5.02']
B = [['1.01', 'string'], ['3.01', 'string'], ['7.01', 'string'], ['10.01', 'string']]
print(set(A).intersection(e[0] for e in B))

from operator import itemgetter
print(set(A).intersection(map(itemgetter(0), B)))

queryset.filter(brand__country__slug=request.GET.get('country'))

queryset = queryset.filter(brand__country__slug=request.GET.get('country'))