Найдите исправленный триггер со встроенными комментариями об ошибках:
-- need to define DELIMITER to something else other than ;
DELIMITER $$
CREATE TRIGGER product_after_insert
AFTER INSERT
ON FRUITS FOR EACH ROW
BEGIN
INSERT INTO products
(category,
product_id)
VALUES
('fruit',
New.ID); -- ; was missing for statement execution
END $$ -- End the Begin clause
DELIMITER ; -- Redefine the delimiter back to ;