mysql 执行注释部分

我是mysql while语句的新手，在终端上执行这行mysql代码效果很好.我在mysql shell中使用了"sql的源路径"命令.

DELIMITER //
CREATE PROCEDURE basic_while()
BEGIN
   SET @stopval := 5;
   SET @counter := 1;
   WHILE @counter <= @stopval DO
      SELECT @counter;
      SET @counter := @counter + 1;
   END WHILE;
END//
DELIMITER ;
CALL basic_while();

输出:

    +----------+
    | @counter |
    +----------+
    |        1 |
    +----------+
    1 row in set (0.00 sec)
    
    +----------+
    | @counter |
    +----------+
    |        2 |
    +----------+
    1 row in set (0.00 sec)
    
    +----------+
    | @counter |
    +----------+
    |        3 |
    +----------+
    1 row in set (0.00 sec)
    
    +----------+
    | @counter |
    +----------+
    |        4 |
    +----------+
    1 row in set (0.00 sec)
    
    +----------+
    | @counter |
    +----------+
    |        5 |
    +----------+

1 row in set (0.00 sec)

现在的问题是，在我注释掉select语句并执行它之后，mysql给了我与上面相同的输出，以及相关的错误.

-- SELECT @counter;

注释掉后的输出:

ERROR 1304 (42000): PROCEDURE basic_while already exists 
   

    +----------+
    | @counter |
    +----------+
    |        1 |
    +----------+
    1 row in set (0.00 sec)
    
    +----------+
    | @counter |
    +----------+
    |        2 |
    +----------+
    1 row in set (0.00 sec)
    
    +----------+
    | @counter |
    +----------+
    |        3 |
    +----------+
    1 row in set (0.00 sec)
    
    +----------+
    | @counter |
    +----------+
    |        4 |
    +----------+
    1 row in set (0.00 sec)
    
    +----------+
    | @counter |
    +----------+
    |        5 |
    +----------+

如何解决这个问题？