我正在尝试使用mysql遍历我的数据库，并将字符串转换为只有数字和。以便将该列从varchar转换为float。然而，当我调用存储过程时，它实际上似乎并没有改变datatable。我希望有人能帮我找出问题所在？

use mydb;
SET GLOBAL log_bin_trust_function_creators = 1;

CREATE TABLE IF NOT EXISTS `docs` (
  `id` int(6) unsigned NOT NULL,
  `rev` int(3) unsigned NOT NULL,
  `content` varchar(200) NOT NULL,
  PRIMARY KEY (`id`,`rev`)
) DEFAULT CHARSET=utf8;
-- INSERT INTO `-- docs` (`id`, `rev`, `content`) VALUES
--   ('1', '1', '0.0 '),
--   ('2', '1', '2,765'),
--   ('3', '1', '*'),
--   ('4', '1', '0.7665');

DROP FUNCTION IF EXISTS floatify; 
DELIMITER //
CREATE FUNCTION floatify(str VARCHAR(200)) RETURNS VARCHAR(16) 
BEGIN
  DECLARE i, len SMALLINT DEFAULT 1; 
  DECLARE ret VARCHAR(16) DEFAULT ''; 
  DECLARE c CHAR(1); 
  SET len = CHAR_LENGTH( str ); 
  REPEAT 
    BEGIN 
      SET c = MID( str, i, 1 ); 
      IF c REGEXP '[0-9|.]' THEN 
        SET ret=CONCAT(ret,c); 
      END IF; 
      SET i = i + 1; 
    END; 
  UNTIL i > len END REPEAT; 
  RETURN ret; 
END//
DELIMITER ;

DROP PROCEDURE IF EXISTS tofloat;
DELIMITER //    
CREATE PROCEDURE tofloat()
BEGIN
DECLARE currentid INT DEFAULT 1;
DECLARE RowCnt BIGINT DEFAULT 0;
SELECT RowCnt = COUNT(*) FROM docs;

WHILE currentid <= RowCnt DO

    UPDATE docs
    SET content = floatify(content)
    WHERE id = currentid;

    SET currentid = currentid + 1 ;
END WHILE;

-- ALTER TABLE docs
-- MODIFY content FLOAT NOT NULL DEFAULT 0 ;
END//
DELIMITER ;

-- select * from docs;
CALL tofloat();
select * from docs;