关于SQL递归查询在不同数据库中的实现方法

//上查
with tmpTree
as
(
	select * from Tree where Id=2
	union all
	select p.* from tmpTree inner join Tree p on  p.Id=tmpTree.ParentId
)
select * from tmpTree

//下查
with tmpTree
as
(
	select * from Tree where Id=2
	union all
	select s.* from tmpTree inner join Tree s on  s.ParentId=tmpTree.Id
)
select * from tmpTree

SELECT *,TId.GetLevel() as [level] FROM Tree2 --获取所有层级

DECLARE @ParentTree hierarchyid
SELECT @ParentTree=TId FROM Tree2 WHERE Id=2
SELECT *,TId.GetLevel()AS  [level] FROM Tree2 WHERE TId.IsDescendantOf(@ParentTree)=1 --获取指定的节点所有下级

DECLARE @ChildTree hierarchyid
SELECT @ChildTree=TId FROM Tree2 WHERE Id=3
SELECT *,TId.GetLevel()AS  [level] FROM Tree2 WHERE @ChildTree.IsDescendantOf(TId)=1 --获取指定的节点所有上级

SELECT *
FROM Tree
START WITH Id=2
CONNECT BY PRIOR ID=ParentId --下查

SELECT *
FROM Tree
START WITH Id=2
CONNECT BY ID= PRIOR  ParentId --上查

//定义一个依据ID查询所有父ID为这个指定的ID的字符串列表，以逗号分隔
CREATE DEFINER=`root`@`localhost` FUNCTION `getChildLst`(rootId int,direction int) RETURNS varchar(1000) CHARSET utf8
BEGIN
 DECLARE sTemp VARCHAR(5000);
   DECLARE sTempChd VARCHAR(1000);
   SET sTemp = ‘$‘;
   IF direction=1 THEN
	 SET sTempChd =cast(rootId as CHAR);
   ELSEIF direction=2 THEN
	 SELECT cast(ParentId as CHAR) into sTempChd FROM Tree WHERE Id=rootId;
   END IF;
    WHILE sTempChd is not null DO
		SET sTemp = concat(sTemp,‘,‘,sTempChd);
		SELECT group_concat(id) INTO sTempChd FROM Tree where (direction=1 and  FIND_IN_SET(ParentId,sTempChd)>0)
		or (direction=2 and  FIND_IN_SET(Id,sTempChd)>0);
    END WHILE;
RETURN sTemp;
END


//查询方法：
select * from tree where find_in_set(id,getChildLst(1,1));--下查
select * from tree where find_in_set(id,getChildLst(1,2));--上查