Shuffle a string with mysql/sql

Question

I was wondering, if there is some way to shuffle the letters of a string in mysql/sql, i.e. something like the pseudocode: SELECT SHUFFLE('abcdef')?

Couldn't find any from http://dev.mysql.com/doc/refman/5.0/en/string-functions.html and searching for it just seems to find solutions for shuffling results, not a string.

Answer 1

Here you go:

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');

See sqlfiddle.com for the output.

Tested successfully with mariadb 10.1 (mysql 5.6 equivalent)