mysql获取拼音首字母（改进版）

DELIMITER $$
USE `test`$$
DROP FUNCTION IF EXISTS `getPY`$$
CREATE FUNCTION `getpy`(in_string VARCHAR(255)) RETURNS VARCHAR(255) CHARSET utf8
BEGIN
DECLARE tmp_str VARCHAR(255) CHARSET utf8 DEFAULT '';
DECLARE str_len SMALLINT DEFAULT 0;
DECLARE tem_loc SMALLINT DEFAULT 0;
DECLARE tmp_char VARCHAR(10) CHARSET utf8 DEFAULT '';
DECLARE tmp_len SMALLINT DEFAULT 0;
DECLARE tmp_rs VARCHAR(255) CHARSET utf8 DEFAULT '';
DECLARE tmp_cc VARCHAR(10) CHARSET utf8 DEFAULT '';
SET tmp_str = in_string;
SET str_len = LENGTH(tmp_str);
WHILE str_len > 0 DO
SET tmp_char = LEFT(tmp_str,1);
SET tmp_cc = tmp_char;
IF LENGTH(tmp_char) > 1
THEN
SET tem_loc = INTERVAL(CONV(HEX(CONVERT(tmp_char USING gbk)),16,10),0xB0A1,0xB0C5,0xB2C1,0xB4EE,0xB6EA,0xB7A2,0xB8C1,0xB9FE,0xBBF7,0xBFA6,0xC0AC,0xC2E8,0xC4C3,0xC5B6,0xC5BE,0xC6DA,0xC8BB,0xC8F6,0xCBFA,0xCDDA,0xCEF4,0xD1B9,0xD4D1);
IF (tem_loc>0 AND tem_loc < 24 )
THEN
SELECT ELT(tem_loc, 'A','B','C','D','E','F','G','H','J','K','L','M','N','O','P','Q','R','S','T','W','X','Y','Z') INTO tmp_cc;
ELSE
SET tmp_cc = '';
END IF;
END IF;
SET tmp_rs = CONCAT(tmp_rs,tmp_cc);
SET tmp_len = CHAR_LENGTH(tmp_char) + 1;
SET tmp_str = SUBSTRING(tmp_str,tmp_len);
SET str_len = LENGTH(tmp_str);
END WHILE;
RETURN tmp_rs;
END$$
DELIMITER ;