mysql sql 根据父级id查询书所有的子孙级数据，或根据子级id查询对应的父级

-- mysql递归查询，mysql中从子类ID查询所有父类（做无限分类经常用到）

SELECT T2.id, T2.channel_path 

FROM ( 

    SELECT 

        @r AS _id, 

        (SELECT @r := parent_id FROM cm_channel WHERE id = _id) AS parent_id, 

        @l := @l + 1 AS lvl 

    FROM 

        (SELECT @r := '2069ac487e2e49ddbdab78cba1e03828', @l := 0) vars, 

        cm_channel h 

    WHERE @r <> 0) T1 

JOIN cm_channel T2 

ON T1._id = T2.id 

ORDER BY T1.lvl DESC;

-- mysql递归查询，mysql中从父类ID查询所有子类（做无限分类经常用到）

DROP FUNCTION IF EXISTS `getChildrenList`;

CREATE FUNCTION `getChildrenList`(rootId VARCHAR(1000))  

RETURNS varchar(1000)  

  

  

BEGIN  

DECLARE sTemp VARCHAR(1000);  

DECLARE sTempChd VARCHAR(1000);  

  

  

SET sTemp = '$';  

SET sTempChd =cast(rootId as CHAR);  

  

  

WHILE sTempChd is not null DO  

SET sTemp = concat(sTemp,',',sTempChd);  

SELECT group_concat(id) INTO sTempChd FROM cm_channel where FIND_IN_SET(parent_id,sTempChd)>0;  

END WHILE;  

RETURN sTemp;  
END  

select * from cm_channel where FIND_IN_SET(id,getChildrenList('e3468f7776bf4cd184d3e05232ab162f'))