Oracle转换MySql之递归start with

Oracle转换Mysql之start with:

oracle转mysql其实很多细节，这边就不一 一 描述了，这边先整理些“坎”吧！

Oracle中start with … ：

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

转换为MySql为：

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

这里并非只要简单改下sql就行，可以看出需要一个函数支撑"getGradeGroupChild",下面提供了这个函数：

DROP FUNCTION IF EXISTS `getGradeGroupChild`;
DELIMITER $$ 
CREATE FUNCTION `getGradeGroupChild`(GROUPCODE VARCHAR(100)) RETURNS VARCHAR(10000) CHARSET utf8
BEGIN
   DECLARE sChildList VARCHAR(10000);
   DECLARE sChildTemp VARCHAR(1000);
   --这里我第一次是要将传进来的GROUPCODE 转换成id，然后去递归查询
   SELECT id INTO sChildTemp FROM grade_group WHERE GROUP_CODE = GROUPCODE;
   WHILE sChildTemp IS NOT NULL DO
	 IF (sChildList IS NOT NULL) THEN 
		SET sChildList = CONCAT(sChildTemp,',',sChildList); 
	 ELSE 
		SET sChildList = CONCAT(sChildTemp); 
	 END IF; 
     SELECT GROUP_CONCAT(id) INTO sChildTemp FROM grade_group 
     WHERE FIND_IN_SET(PARENT_ID, sChildTemp)>0;
   END WHILE;
   RETURN sChildList;
 END$$
DELIMITER ;