mysql 定义cursor出错

DELIMITER //
CREATE PROCEDURE my_procedure()
BEGIN
    DECLARE cur CURSOR FOR SELECT * FROM my_table;
END //
DELIMITER ;

DELIMITER //
CREATE PROCEDURE my_procedure()
BEGIN
    DECLARE done INT DEFAULT FALSE;
    DECLARE v_id INT;
    DECLARE v_name VARCHAR(255);
    DECLARE cur CURSOR FOR SELECT id, name FROM my_table;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO v_id, v_name;
        IF done THEN
            LEAVE read_loop;
        END IF;
        -- 处理数据
    END LOOP;

    CLOSE cur;
END //
DELIMITER ;

ERROR 1045 (28000): Access denied for user 'user'@'localhost' (using password: YES)

GRANT EXECUTE ON my_database.* TO 'user'@'localhost';

ERROR 2006 (HY000): MySQL server has gone away

[mysqld]
wait_timeout = 28800
interactive_timeout = 28800