支持utf8的mysql urldecode funtion

 不要吐槽我为什么用sql语句来做urldecode。。。 
但是当你遇到这种情况而且搜到的sql都只支持英文时，这篇文章就有用了 

参考文章： 
http://psoug.org/snippet/url_decode_that_respects_utf8_characters_502.htm 
http://www.w3schools.com/tags/ref_urlencode.asp 

原方法在替换'%0A'时转换失败，加多一句处理，其他特殊符号均可参照表格用同样方法提前替换。 

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Sql代码：

DELIMITER $$
DROP FUNCTION
IF EXISTS `url_decode`$$

CREATE DEFINER = `root`@`%` FUNCTION `url_decode` (original_text TEXT) RETURNS TEXT CHARSET utf8
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 ;
					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 result_text = CONVERT (
						UNHEX(
							REPLACE (encoded_text, "%", "")
						) USING utf8
					) ;
					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$$

DELIMITER ;