MySql custom function for checking if a string is intended to represent a number

fn_isnumeric.sql

DROP FUNCTION IF EXISTS `fn_isnumeric`;

DELIMITER //

CREATE FUNCTION `fn_isnumeric`(
    s VARCHAR(100))
RETURNS TINYINT
NO SQL
BEGIN

    RETURN IFNULL(s, '') REGEXP '^[:space:]*[+-]?[£\$\€]?([0-9]*\.?[0-9]+|[0-9]{1,3}(,[0-9]{3})*(\.[0-9]+)?)[:space:]*$';

END //

DELIMITER ;