select * from 
  	grade_group gg 
  start with gg.group_code=#{groupCode} 
  connect by  gg.parent_id= prior gg.id
  order by gg.group_level

  SELECT
      *
  FROM
      grade_group
  WHERE FIND_IN_SET(ID, getGradeGroupChild(#{groupCode}))
  ORDER BY group_level

DROP FUNCTION IF EXISTS `getGradeGroupChild`;
DELIMITER $$ 
CREATE FUNCTION `getGradeGroupChild`(GROUPCODE VARCHAR(100)) RETURNS VARCHAR(10000) CHARSET utf8
BEGIN
   DECLARE sChildList VARCHAR(10000);
   DECLARE sChildTemp VARCHAR(1000);
   --這里我第一次是要將傳進來的GROUPCODE 轉換成id，然后去遞歸查詢
   SELECT id INTO sChildTemp FROM grade_group WHERE GROUP_CODE = GROUPCODE;
   WHILE sChildTemp IS NOT NULL DO
	 IF (sChildList IS NOT NULL) THEN 
		SET sChildList = CONCAT(sChildTemp,',',sChildList); 
	 ELSE 
		SET sChildList = CONCAT(sChildTemp); 
	 END IF; 
     SELECT GROUP_CONCAT(id) INTO sChildTemp FROM grade_group 
     WHERE FIND_IN_SET(PARENT_ID, sChildTemp)>0;
   END WHILE;
   RETURN sChildList;
 END$$
DELIMITER ;