regex - MySQL strip non-numeric characters to compare

Question

I'm looking to find records in a table that match a specific number that the user enters. So, the user may enter 12345, but this could be 123zz4-5 in the database.

I imagine something like this would work, if PHP functions worked in MySQL.

SELECT * FROM foo WHERE preg_replace("/[^0-9]/","",bar) = '12345'

What's the equivalent function or way to do this with just MySQL?

Speed is not important.

Answer 1

I realise that this is an ancient topic but upon googling this problem I couldn't find a simple solution (I saw the venerable agents but think this is a simpler solution) so here's a function I wrote, seems to work quite well.

DROP FUNCTION IF EXISTS STRIP_NON_DIGIT;
DELIMITER $$
CREATE FUNCTION STRIP_NON_DIGIT(input VARCHAR(255))
   RETURNS VARCHAR(255)
BEGIN
   DECLARE output   VARCHAR(255) DEFAULT '';
   DECLARE iterator INT          DEFAULT 1;
   WHILE iterator < (LENGTH(input) + 1) DO
      IF SUBSTRING(input, iterator, 1) IN ( '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' ) THEN
         SET output = CONCAT(output, SUBSTRING(input, iterator, 1));
      END IF;
      SET iterator = iterator + 1;
   END WHILE;
   RETURN output;
END
$$