mysql-MySQL:为什么这样的小改动会造成存储过程错误呢？

mysql

<code> DELIMITER $$                  USE mysql$$DROP PROCEDURE IF EXISTS demo$$CREATE PROCEDURE demo(_id INT, _content VARCHAR(64))    BEGIN                  SET @id = _id;    SET @content = _content;                                                                                          PREPARE stmt FROM "INSERT INTO blog (id, content) VALUES(?, ?)";    EXECUTE stmt USING @id, @content;    DEALLOCATE PREPARE stmt;END$$DELIMITER ;DELIMITER $$</code>

如果改写成如下就会报错：

<code> DELIMITER $$USE mysql$$DROP PROCEDURE IF EXISTS demo$$CREATE PROCEDURE demo(_id INT, _content VARCHAR(64))    BEGIN                  -- set @id = _id;    -- set @content = _content;    PREPARE stmt FROM "INSERT INTO blog (id, content) VALUES(?, ?)";    EXECUTE stmt USING _id, _content;    DEALLOCATE PREPARE stmt;END$$DELIMITER ;</code>

<code> 错误代码： 1064You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '_id, _content;    DEALLOCATE PREPARE stmt;END' at line 7</code>