PostgreSQL中的Base58编码器功能

Question

我在Github
Gist中
找到了针对Base58编码器的MySQL函数
。

DELIMITER $$

CREATE FUNCTION base58_encode (num int) RETURNS varchar(255)
  DETERMINISTIC

BEGIN
  DECLARE alphabet varchar(255);
  DECLARE base_count int DEFAULT 0;
  DECLARE encoded varchar(255);
  DECLARE divisor DECIMAL(10,4);
  DECLARE mode int DEFAULT 0;

  SET alphabet = '123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ';
  SET base_count = CHAR_LENGTH(alphabet);
  SET encoded = "";

  WHILE num  >= base_count DO
    SET divisor = num / base_count;
    SET mode = (num - (base_count* TRUNCATE(divisor,0)));
    SET encoded = CONCAT(SUBSTRING(alphabet FROM mode+1 FOR 1), encoded);
    SET num = TRUNCATE(divisor,0);
  END WHILE;

  SET encoded = CONCAT(SUBSTRING(alphabet FROM num+1 FOR 1), encoded);

  RETURN (encoded);

END

我是新手PostgreSQL，很难将上述函数转换为PostgreSQL函数。

PostgreSQL上面的SQL代码片段对Base58 Encoder的等效功能如何？

Answer 1

我想出的PostgreSQL中的等效函数如下。

CREATE FUNCTION base58_encode(num INT)
  RETURNS VARCHAR(255) AS $encoded$

DECLARE
  alphabet   VARCHAR(255);
  base_count INT DEFAULT 0;
  encoded    VARCHAR(255);
  divisor    DECIMAL(10, 4);
  mod        INT DEFAULT 0;

BEGIN
  alphabet := '123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ';
  base_count := char_length(alphabet);
  encoded := '';

  WHILE num >= base_count LOOP
    divisor := num / base_count;
    mod := (num - (base_count * trunc(divisor, 0)));
    encoded := concat(substring(alphabet FROM mod + 1 FOR 1), encoded);
    num := trunc(divisor, 0);
  END LOOP;

  encoded = concat(substring(alphabet FROM num + 1 FOR 1), encoded);

  RETURN (encoded);

END; $encoded$
LANGUAGE PLPGSQL;