CTE 遍历备份层次结构?
我可以在分层数据模型中找到给定记录的所有子项(请参阅下面的代码),但我不确定如何使用给定的子 ID 遍历备份父/子链。 谁能指出我正确的方向来弄清楚如何做到这一点? 这在 Linq to SQL 中也可能吗?
WITH TaskHierarchy (TaskID, [Subject], ParentID, HierarchyLevel, HierarchyPath) AS
(
-- Base case
SELECT
TaskID,
[Subject],
ParentID,
1 as HierarchyLevel,
CONVERT(VARCHAR(MAX),'/') AS HierarchyPath
FROM Task
WHERE TaskID = 2
UNION ALL
-- Recursive step
SELECT
t.TaskID,
t.Subject,
t.ParentID,
th.HierarchyLevel + 1 AS HierarchyLevel,
CONVERT(varchar(MAX),th.HierarchyPath + CONVERT(VARCHAR(32),t.ParentID) + '/') AS HierarchyPath
FROM Task t
INNER JOIN TaskHierarchy th ON
t.ParentID = th.TaskID
)
SELECT *
FROM TaskHierarchy
ORDER BY HierarchyLevel, [Subject]
I can find all the children of a given record in a hierarchical data model (see code below) but I'm not sure how to traverse back up the Parent/Child chain with a given Child ID. Can anyone point me in the right direction to figure out how to do this? Is this possible in Linq to SQL as well?
WITH TaskHierarchy (TaskID, [Subject], ParentID, HierarchyLevel, HierarchyPath) AS
(
-- Base case
SELECT
TaskID,
[Subject],
ParentID,
1 as HierarchyLevel,
CONVERT(VARCHAR(MAX),'/') AS HierarchyPath
FROM Task
WHERE TaskID = 2
UNION ALL
-- Recursive step
SELECT
t.TaskID,
t.Subject,
t.ParentID,
th.HierarchyLevel + 1 AS HierarchyLevel,
CONVERT(varchar(MAX),th.HierarchyPath + CONVERT(VARCHAR(32),t.ParentID) + '/') AS HierarchyPath
FROM Task t
INNER JOIN TaskHierarchy th ON
t.ParentID = th.TaskID
)
SELECT *
FROM TaskHierarchy
ORDER BY HierarchyLevel, [Subject]
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啊,我明白了:
Ah, I figured it out: