用mysql / sql洗牌

干得好：

DELIMITER //DROP FUNCTION IF EXISTS shuffle //CREATE FUNCTION shuffle(    v_chars TEXT)RETURNS TEXTNOT DETERMINISTIC -- multiple RAND()'sNO SQLSQL SECURITY INVOKERCOMMENT ''BEGIN    DECLARE v_retval TEXT DEFAULT '';    DECLARE u_pos    INT UNSIGNED;    DECLARE u        INT UNSIGNED;    SET u = LENGTH(v_chars);    WHILE u > 0    DO      SET u_pos = 1 + FLOOR(RAND() * u);      SET v_retval = CONCAt(v_retval, MId(v_chars, u_pos, 1));      SET v_chars = CONCAt(LEFt(v_chars, u_pos - 1), MId(v_chars, u_pos + 1, u));      SET u = u - 1;    END WHILE;    RETURN v_retval;END;//DELIMITER ;SELECT shuffle('abcdef');

有关输出，请参见sqlfiddle.com。

已使用mariadb 10.1成功测试（相当于mysql 5.6）