MySQL에서 Levenshtein 거리 함수를 구현하는 방법은 무엇입니까?

DELIMITER $$
CREATE FUNCTION levenshtein(str1 VARCHAR(255), str2 VARCHAR(255))
  RETURNS INT
  DETERMINISTIC
BEGIN
  DECLARE str1len, str2len, i, j, cost, c, vtemp INT;
  DECLARE vmatrix VARCHAR(255);

  CALL max(length(str1), length(str2), str1len, str2len);

  SET vtemp = power(2, str2len) * power(2, str1len);
  SET vmatrix = LPAD('0', vtemp, '0');

  SET i = 1;
  WHILE i <= str1len DO
    SET t = SUBSTR(str1, i, 1);
    SET j = 1;
    WHILE j <= str2len DO
      SET s = SUBSTR(str2, j, 1);

      IF i = 1 THEN
        CALL min3(j, vmatrix, i * j, j + 1);
      END IF;
      IF j = 1 THEN
        CALL min3(i, vmatrix, i, i * str2len + j);
      END IF;

      SET cost = IF(t = s, 0, 1);
      CALL min3(vmatrix, vmatrix, cost + vmatrix, i * str2len + j);

      CALL min3(i, vmatrix, vmatrix, i * str2len + j + 1);
      CALL min3(j, vmatrix, vmatrix, (i + 1) * str2len + j);

      SET j = j + 1;
    END WHILE;
  SET i = i + 1;
END WHILE;

  RETURN vmatrix;
END
$$
DELIMITER ;

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

$sql = 'SELECT levenshtein(?, ?) AS distance';
$stmt = $conn->prepare($sql);
$stmt->bind_param('ss', $str1, $str2);
$stmt->execute();
$result = $stmt->get_result();
while ($row = $result->fetch_assoc()) {
  $distance = $row['distance'];
}