How to add levenshtein function in mysql?

I have connected to my MySQL server and simply executed this statement in MySQL Workbench, and it simply worked - I now have new function levenshtein().

For example, this works as expected:

SELECT levenshtein('abcde', 'abced')2

DELIMITER $$CREATE FUNCTION levenshtein( s1 VARCHAR(255), s2 VARCHAR(255) ) RETURNS INT DETERMINISTIC BEGIN DECLARE s1_len, s2_len, i, j, c, c_temp, cost INT; DECLARE s1_char CHAR; -- max strlen=255 DECLARE cv0, cv1 VARBINARY(256); SET s1_len = CHAR_LENGTH(s1), s2_len = CHAR_LENGTH(s2), cv1 = 0x00, j = 1, i = 1, c = 0; IF s1 = s2 THEN   RETURN 0; ELSEIF s1_len = 0 THEN   RETURN s2_len; ELSEIF s2_len = 0 THEN   RETURN s1_len; ELSE   WHILE j <= s2_len DO     SET cv1 = CONCAT(cv1, UNHEX(HEX(j))), j = j + 1;   END WHILE;   WHILE i <= s1_len DO     SET s1_char = SUBSTRING(s1, i, 1), c = i, cv0 = UNHEX(HEX(i)), j = 1;     WHILE j <= s2_len DO       SET c = c + 1;       IF s1_char = SUBSTRING(s2, j, 1) THEN          SET cost = 0; ELSE SET cost = 1;       END IF;       SET c_temp = CONV(HEX(SUBSTRING(cv1, j, 1)), 16, 10) + cost;       IF c > c_temp THEN SET c = c_temp; END IF;         SET c_temp = CONV(HEX(SUBSTRING(cv1, j+1, 1)), 16, 10) + 1;         IF c > c_temp THEN            SET c = c_temp;          END IF;         SET cv0 = CONCAT(cv0, UNHEX(HEX(c))), j = j + 1;     END WHILE;     SET cv1 = cv0, i = i + 1;   END WHILE; END IF; RETURN c; END$$DELIMITER ;

the web paged linked in question is dead. By the way, the function's create code is here:

DELIMITER $$CREATE FUNCTION levenshtein( s1 varchar(255), s2 varchar(255) ) returns int deterministic BEGIN   DECLARE s1_len,     s2_len,     i,     j,     c,     c_temp,     cost          int;   declare s1_char char;   -- max strlen=255   declare cv0,     cv1 varbinary(256);   set s1_len = char_length(s1),     s2_len = char_length(s2),     cv1 = 0x00,     j = 1,     i = 1,     c = 0;   if s1 = s2 THEN   RETURN 0; elseif s1_len = 0 THEN   RETURN s2_len; elseif s2_len = 0 THEN   RETURN s1_len;   else   WHILE j <= s2_len do   SET cv1 = concat(cv1, unhex(hex(j))),     j = j + 1; endWHILE;WHILE i <= s1_len do SET s1_char = substring(s1, i, 1),   c = i,   cv0 = unhex(hex(i)),   j = 1;WHILE j <= s2_len do SET c = c + 1;IF s1_char = Substring(s2, j, 1) then SET cost = 0; else SET cost = 1;ENDIF;SET c_temp = conv(hex(substring(cv1, j, 1)), 16, 10) + cost;IF c > c_temp thenSET c = c_temp;ENDIF;SET c_temp = conv(hex(substring(cv1, j+1, 1)), 16, 10) + 1;IF c > c_temp thenSET c = c_temp;ENDIF;SET cv0 = concat(cv0, unhex(hex(c))),   j = j + 1;ENDWHILE;SET cv1 = cv0,   i = i + 1;ENDWHILE;ENDIF;RETURN c;END;DELIMITER ;

I hope it helps some body!