mysql根据行号来修改

CREATE TABLE users (
    id INT PRIMARY KEY,
    name VARCHAR(50),
    age INT
);

UPDATE users
SET age = 30
ORDER BY id
LIMIT 1 OFFSET 1;

DELIMITER //

CREATE PROCEDURE UpdateAgeByRowNumber(IN rowNum INT, IN newAge INT)
BEGIN
    DECLARE done INT DEFAULT FALSE;
    DECLARE currentId INT;
    DECLARE cur CURSOR FOR SELECT id FROM users ORDER BY id;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO currentId;
        IF done THEN
            LEAVE read_loop;
        END IF;

        IF rowNum = 0 THEN
            UPDATE users SET age = newAge WHERE id = currentId;
            LEAVE read_loop;
        END IF;

        SET rowNum = rowNum - 1;
    END LOOP;

    CLOSE cur;
END //

DELIMITER ;

CALL UpdateAgeByRowNumber(1, 30);  -- 修改第2行的age为30