mysql版本（5.5、6等等）尚未支持循环递归查询，和sqlserver、oracle相比，mysql难于在树状表中层层遍历的子节点。本程序重点参考了下面的资料，写了两个sql存储过程，子节点查询算是照搬了，父节点查询是逆思维弄的。
表结构和表数据就不公示了，查询的表user_role，主键是id，每条记录有parentid字段（对应该记录的父节点，当然，一个父节点自然会有一个以上的子节点嘛）
CREATE FUNCTION `getChildList`(rootId INT)
RETURNS varchar(1000)
BEGIN
DECLARE sChildList VARCHAR(1000);
DECLARE sChildTemp VARCHAR(1000);
SET sChildTemp =cast(rootId as CHAR);
WHILE sChildTemp is not null DO
IF (sChildList is not null) THEN
SET sChildList = concat(sChildList,',',sChildTemp);
ELSE
SET sChildList = concat(sChildTemp);
END IF;
SELECT group_concat(id) INTO sChildTemp FROM user_role where FIND_IN_SET(parentid,sChildTemp)>0;
END WHILE;
RETURN sChildList;
END;
/*获取子节点*/
/*调用: 1、select getChildList(0) id; 2、select * 5From user_role where FIND_IN_SET(id, getChildList(2));*/
CREATE FUNCTION `getParentList`(rootId INT)
RETURNS varchar(1000)
BEGIN
DECLARE sParentList varchar(1000);
DECLARE sParentTemp varchar(1000);
SET sParentTemp =cast(rootId as CHAR);
WHILE sParentTemp is not null DO
IF (sParentList is not null) THEN
SET sParentList = concat(sParentTemp,',',sParentList);
ELSE
SET sParentList = concat(sParentTemp);
END IF;
SELECT group_concat(parentid) INTO sParentTemp FROM user_role where FIND_IN_SET(id,sParentTemp)>0;
END WHILE;
RETURN sParentList;
END;
/*获取父节点*/
/*调用: 1、select getParentList(6) id; 2、select * From user_role where FIND_IN_SET(id, getParentList(2));*/
