MySQL 获取汉字拼音首字母

CREATE FUNCTION `fn_get_pinyin_initial`(PARAM VARCHAR(255)) RETURNS VARCHAR(20) CHARSET utf8
    DETERMINISTIC
BEGIN 
    DECLARE V_RETURN VARCHAR(255);
        DECLARE V_RESULT VARCHAR(255);
    DECLARE V_FIRST_CHAR VARCHAR(2);
        SET V_RESULT='';
        SET V_FIRST_CHAR=PARAM;
        WHILE LENGTH(V_FIRST_CHAR)>0 DO 
    SET V_FIRST_CHAR = UPPER(LEFT(PARAM,1));
        
    SET V_RETURN = V_FIRST_CHAR;
    IF LENGTH( V_FIRST_CHAR) <> CHARACTER_LENGTH( V_FIRST_CHAR ) THEN
    SET V_RETURN = ELT(INTERVAL(CONV(HEX(LEFT(CONVERT(PARAM USING gbk),1)),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),
    'A','B','C','D','E','F','G','H','J','K','L','M','N','O','P','Q','R','S','T','W','X','Y','Z');
    END IF;
        SET V_RESULT=CONCAT(V_RESULT,V_RETURN);
        -- INSERT INTO T VALUES(V_RETURN);
        SET PARAM = SUBSTRING(PARAM,2,LENGTH(PARAM)-1);
        END WHILE;
    RETURN V_RESULT;
END