URL编码函数：
CREATE DEFINER=`root`@`localhost` FUNCTION `url_encode`(str VARCHAR(4096) CHARSET utf8mb4) RETURNS varchar(4096) CHARSET utf8mb4
BEGIN
DECLARE sub VARCHAR(1) CHARSET utf8mb4;
DECLARE val BIGINT DEFAULT 0;
DECLARE ind INT DEFAULT 1;
DECLARE oct INT DEFAULT 0;
DECLARE ret VARCHAR(4096) DEFAULT '';
DECLARE octind INT DEFAULT 0;
IF str is NULL THEN
RETURN NULL;
ELSE SET ret = '';
WHILE ind <= CHAR_LENGTH(str) DO
SET sub = MID(str, ind, 1);
SET val = ORD(sub);
IF NOT (val BETWEEN 48 AND 57 OR
val BETWEEN 65 AND 90 OR
val BETWEEN 97 AND 122 OR
val IN (45, 46, 95, 126)) THEN
SET octind = OCTET_LENGTH(sub);
WHILE octind > 0 DO
SET oct = (val >> (8 * (octind - 1)));
SET ret = CONCAT(ret, '%', LPAD(HEX(oct), 2, 0));
SET val = (val & (POWER(256, (octind - 1)) - 1));
SET octind = (octind - 1);
END WHILE;
ELSE
SET ret = CONCAT(ret, sub);
END IF;
SET ind = (ind + 1);
END WHILE;
END IF;
RETURN ret;
END
URL解码函数：
CREATE DEFINER=`root`@`localhost` FUNCTION `url_decode`(original_text TEXT CHARSET utf8mb4) RETURNS text CHARSET utf8mb4
BEGIN
DECLARE new_text TEXT DEFAULT NULL;
DECLARE pointer INT DEFAULT 1;
DECLARE end_pointer INT DEFAULT 1;
DECLARE encoded_text TEXT DEFAULT NULL;
DECLARE result_text TEXT DEFAULT NULL;
DECLARE rep_text TEXT DEFAULT NULL;
DECLARE unhex_text TEXT DEFAULT NULL;
SET new_text = REPLACE(original_text,'+',' ');
SET new_text = REPLACE(new_text,'%0A','\r\n');
SET pointer = LOCATE('%', new_text);
WHILE pointer <> 0 && pointer < (CHAR_LENGTH(new_text) - 2) DO
SET end_pointer = pointer + 3;
WHILE MID(new_text, end_pointer, 1) = '%' DO
SET end_pointer = end_pointer+3;
END WHILE;
SET encoded_text = MID(new_text, pointer, end_pointer - pointer);
SET rep_text = REPLACE(encoded_text, '%', '');
SET unhex_text = UNHEX(rep_text);
SET result_text = CONVERT(unhex_text USING utf8mb4);
SET new_text = REPLACE(new_text, encoded_text, result_text);
SET pointer = LOCATE('%', new_text, pointer + CHAR_LENGTH(result_text));
END WHILE;
RETURN new_text;
END