Tady to je:
DELIMITER //
DROP FUNCTION IF EXISTS shuffle //
CREATE FUNCTION shuffle(
v_chars TEXT
)
RETURNS TEXT
NOT DETERMINISTIC -- multiple RAND()'s
NO SQL
SQL SECURITY INVOKER
COMMENT ''
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');
Viz sqlfiddle.com pro výstup.
Úspěšně testováno s mariadb 10.1 (ekvivalent mysql 5.6)