將根節點添加到SQL CTE層次結構樹

Question

我的查詢工作基於CTE Recursion to get tree hierarchy顯示了我的層次結構樹。

結果看起來像

- Category 
- Category 
- - SubCategory 
- - - Sub SubCategory 
- - SubCategory 
... 

我想根節點添加到我的樹，但我沒有看到如何做到這一點。我如何將根節點添加到這棵樹？

編輯：我目前的查詢看起來是這樣的：

;WITH Tree as 
(
    Select Parent_ID, ParentDescr, Node_ID, Node, 1 as Level, cast(Node as varchar(max)) as Path 
    FROM Nodes 
    WHERE ParentDescr = 'Root' 

    UNION ALL 

    Select A.Parent_ID, A.ParentDescr, A.Node_ID, A.Node, Level + 1 as Level, cast(B.Path + ' | ' + A.Node as varchar(max)) as Path 
    FROM Nodes A 
    INNER JOIN Tree B ON A.PARENT_ID = B.Node_ID 
    WHERE A.ParentDescr <> 'Root' 
) 
SELECT REPLICATE(' - ', level) + Node as Tree, Path, Node_ID, ParentDescr, PARENT_ID 
from Tree 
ORDER BY Path asc 

下面是一些樣本數據：

SELECT * 
FROM (
VALUES 
('123','Root',NULL,NULL), 
('456','Category','123','Root'), 
('789','SubCategory','456','Category'), 
('012','Sub SubCategory','789','SubCategory'), 
('345','Category','123','Root')) AS vtable 
([Class_ID],[Class],[Parent_ID],[ParentClass]) 

結果應該是這樣的：

Root 
- Category 
- - SubCategory 
- - - Sub SubCategory 
- Category 

Answer 1

其實，我想你只需要改變這一點：

WHERE ParentDescr = 'Root' 

要這樣：

WHERE Node = 'Root' 

，同樣，改變這種：

WHERE A.ParentDescr <> 'Root' 

要這樣：

WHERE A.Node <> 'Root' 

編輯：

根據您的樣本數據，我的改變應該有工作d如果你正確實施它們。驗證您的新查詢是這樣的：

;WITH Tree as 
(
    Select Parent_ID, ParentDescr, Node_ID, Node, 1 as Level, cast(Node as varchar(max)) as Path 
    FROM Nodes 
    WHERE Node = 'Root' 

    UNION ALL 

    Select A.Parent_ID, A.ParentDescr, A.Node_ID, A.Node, Level + 1 as Level, cast(B.Path + ' | ' + A.Node as varchar(max)) as Path 
    FROM Nodes A 
    INNER JOIN Tree B ON A.PARENT_ID = B.Node_ID 
    WHERE A.Node <> 'Root' --this line really isn't even necessary 
) 
SELECT REPLICATE(' - ', level) + Node as Tree, Path, Node_ID, ParentDescr, PARENT_ID 
from Tree 
ORDER BY Path asc 

它應該工作。