DROP PROCEDURE IF EXISTS `update_product_category`;
DELIMITER ;;
CREATE PROCEDURE `update_product_category` (
    IN p_category INT,
    IN p_product_id INT,
    IN p_user_id INT,
    OUT p_status INT
)
proc:BEGIN
    IF p_category IS NULL THEN
        SET p_status = -1;
        LEAVE proc;
    END IF;
    UPDATE products SET category = p_category WHERE user_id = p_user_id AND id = p_product_id;
    SET p_status = 0;
END ;;
DELIMITER ;