What's wrong w/ MySql Statement (Function) - mysql

Question

I'm using MySql57
What's wrong with this script?(I'm Mysql newbie)
Error Code: 1064. You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '= 'A0001'; ELSE BEGIN gubun1 = LEFT(cur_max,0,1); gu' at line 10
DELIMITER $$
CREATE FUNCTION narae.FN_GET_GUBUN_MAX() RETURNS varchar(100)
BEGIN
DECLARE cur_max varchar(100);
DECLARE gubun1 varchar(1);
DECLARE gubun2 varchar(100);
DECLARE RTN_VAL varchar(100);
SELECT IFNULL(MAX(gubun_code),'A0001') INTO cur_max from gubun_code;
IF cur_max = 'A0001' THEN RTN_VAL = 'A0001';
ELSE
BEGIN
gubun1 = LEFT(cur_max,0,1);
gubun2 =
LPAD(CONVERT(CONVERT(RIGHT(cur_max,4),UNSIGNED)+1,CHAR),4,'0');
RTN_VAL = CONCAT(gubun1,gubun2);
END
RETURN RTN_VAL;
END $$
DELIMITER ;

Answer 1

There are several errors in the function. I think this might work:
DELIMITER $$
CREATE FUNCTION narae.FN_GET_GUBUN_MAX() RETURNS varchar(100)
BEGIN
DECLARE v_cur_max varchar(100);
DECLARE v_RTN_VAL varchar(100);
SELECT COALESCE(MAX(gubun_code), 'A0001')
INTO v_cur_max
FROM gubun_code;
IF cur_max = 'A0001' THEN
SET v_RTN_VAL = 'A0001';
ELSE
SET v_RTN_VAL = CONCAT(LEFT(cur_max, 1), RIGHT(cur_max, 4) + 1);
END IF;
RETURN v_RTN_VAL;
END $$
DELIMITER ;
I would further simplify this by doing all the logic in the SQL statement, but this seems to be in the spirit of your solution.