mysql中查询结果只保留数字函数

CREATE DEFINER=`root`@`%` FUNCTION `getNum`(str varchar(255) ) RETURNS varchar(255) CHARSET utf8mb4
BEGIN
DECLARE strlength INT DEFAULT 0;
DECLARE temp varchar(50) default '';
SET strlength=CHAR_LENGTH(str);
WHILE strlength > 0 DO
	IF (ASCII(mid(str,strlength,1))>47 and ASCII(mid(str,strlength,1))<58 ) THEN
		SET temp=concat (temp,mid(str,strlength,1));
	END IF;
		SET strlength = strlength - 1;
		END WHILE;
	RETURN REVERSE (temp);
END

例如：

select getNum('你HIA啊123') FROM dual

结果如图