mysql 전화번호 masking

DELIMITER //
CREATE DEFINER=`mcouponbo`@`%` FUNCTION `getMaskPhone`(`v_code` varchar(50)) RETURNS varchar(50) CHARSET utf8
BEGIN
declare return_value varchar(50);

SET v_code = replace(v_code, '-', '');

SELECT
CASE WHEN CHAR_LENGTH(v_code) < 9 THEN v_code
ELSE
CASE SUBSTRING(v_code, 1, 2) WHEN '02' THEN
CONCAT('02', '-', REPEAT('*', CHAR_LENGTH(v_code) - 6), '-', SUBSTRING(v_code, CHAR_LENGTH(v_code) - 3, CHAR_LENGTH(v_code)))
ELSE
CONCAT(SUBSTRING(v_code, 1, 3), '-', REPEAT('*', CHAR_LENGTH(v_code) - 7), '-', SUBSTRING(v_code, CHAR_LENGTH(v_code) - 3, CHAR_LENGTH(v_code)))
END
END INTO return_value;

RETURN return_value;
END//
DELIMITER ;