Mysql Query to find distinct characters in a string

Question

Is there a way to write recursive query in mysql. Equivalent of connect by (level or Prior) in oracle. I searched google as well as stackoverflow and there is no direct eqivalent. But is there any work around to get it.

I have a string, i have to iterate through individual characters in the string and print only the distinct characters of the string.

Input:

recursive

Output:

recusiv

Answer 1

I came up with this "simple" solution.

Functions used:

• GROUP_CONCAT: http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat

• SUBSTRING http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_substring

Live demo: http://www.sqlfiddle.com/#!2/d41d8/19186

SELECT
  GROUP_CONCAT( chars.c SEPARATOR '') AS allchars
FROM (

  SELECT DISTINCT 
    SUBSTRING( str.str, pos.pos, 1 ) AS c

  FROM 

  ( SELECT x1.x + x2.x*10 AS pos
    FROM
    ( SELECT 0 AS x UNION ALL
      SELECT 1 UNION ALL
      SELECT 2 UNION ALL
      SELECT 3 UNION ALL
      SELECT 4 UNION ALL
      SELECT 5 UNION ALL
      SELECT 6 UNION ALL
      SELECT 7 UNION ALL
      SELECT 8 UNION ALL
      SELECT 9
    ) AS x1
    INNER JOIN
    ( SELECT 0 AS x UNION ALL
      SELECT 1 UNION ALL
      SELECT 2 UNION ALL
      SELECT 3 UNION ALL
      SELECT 4 UNION ALL
      SELECT 5 UNION ALL
      SELECT 6 UNION ALL
      SELECT 7 UNION ALL
      SELECT 8 UNION ALL
      SELECT 9
    ) AS x2
  ) AS pos

  INNER JOIN

  ( SELECT 'recursive' AS str UNION ALL
    SELECT 'XYZ'
  ) AS str

) AS chars