mysql如何得到随机字符串

SELECT UUID();

SELECT CONCAT(
    SUBSTRING(MD5(RAND()), 1, 2),
    SUBSTRING(MD5(RAND()), 3, 2),
    SUBSTRING(MD5(RAND()), 5, 2),
    SUBSTRING(MD5(RAND()), 7, 2),
    SUBSTRING(MD5(RAND()), 9, 2)
) AS random_string;

DELIMITER //

CREATE FUNCTION GenerateRandomString(length INT) RETURNS VARCHAR(255)
BEGIN
    DECLARE chars_str VARCHAR(100) DEFAULT 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
    DECLARE return_str VARCHAR(255) DEFAULT '';
    DECLARE i INT DEFAULT 0;
    WHILE i < length DO
        SET return_str = CONCAT(return_str, SUBSTRING(chars_str, FLOOR(RAND() * LENGTH(chars_str) + 1), 1));
        SET i = i + 1;
    END WHILE;
    RETURN return_str;
END //

DELIMITER ;

SELECT GenerateRandomString(10);