给定下表:
create table TreeNode
(
ID int not null primary key,
ParentID int null foreign key references TreeNode (ID)
)
我如何编写一个公用表表达式从根(WHERE ParentID IS NULL)开始并遍历其后代,直到结果集包含某个目标节点(例如,WHERE ID = n)?从目标节点开始并向上遍历到根节点很容易,但这不会生成相同的结果集。具体来说,不包括与目标节点具有相同父节点的节点。
我的第一次尝试是:
with Tree as
(
select
ID,
ParentID
from
TreeNode
where
ParentID is null
union all select
a.ID,
a.ParentID
from
TreeNode a
inner join Tree b
on b.ID = a.ParentID
where
not exists (select * from Tree where ID = @TargetID)
)
这给出了错误:Recursive member of a common table expression 'Tree' has multiple recursive references.
注意:我只对自上而下的遍历感兴趣。