N层父/子面包屑路径-自下而上循环

Question

I am trying to building a breadcrumb trail based on a parent/child relationship in a SQL database table. I have done these in the past, but what I need to do now is walk my way up through the hierarchy from the bottom up (backwards).

Here is what my DataTable looks like:

DocID | ParentDocID | Name
7 | 0 | Images (Root)
24 | 7 | JPG (Level 2)
34 | 24 | Size (Level 3)

So this is an N-tiered architecture. I always know what level I am at via a query string variable. I need to loop from the bottom up so that a user can bookmark what level in the tier structure they are at. I am having trouble figuring this out. I cannot use session or viewstate.

Desired Results:

User goes to this link: Default.aspx?DocId=34 – Then they see the breadcrumb trail as such:
Home > Images > JPG > Size

Default.aspx?DocId=24 – Then they see the breadcrumb trail as such:
Home > Images > JPG

The “Home” element I have hard-coded. I also need each item in the trail to link except for the level you are on.

I would rather this be done in C# code. I also am open to SQL level Stored Procedure options.

Any help would be greatly appreciated. Thank-you in advance!

Here is some SQL I am trying but not getting the results I need. I hope this helps:

WITH Hierachy([DocID], [ParentDocID], [Name], [Level]
AS
(
SELECT [DocID], [ParentDocID], [Name], 0 AS [Level]
FROM [Documents] d
WHERE (d.[ParentDocID] = 7) AND ([Folder] = 1) AND ([Status] = 'A') AND ([AppGroupID] = 4)
UNION ALL
SELECT d.[DocID], d.[ParentDocID], d.[Name], dh.[Level] + 1
FROM [Documents] d
INNER JOIN Hierachy dh
--ON d.ParentDocID = dh.DocID
ON dh.[ParentDocID] = d.[DocID] -- bottom up apporach
WHERE ([Folder] = 1) AND ([Status] = 'A') AND ([AppGroupID] = 4)
)
SELECT [DocID], [ParentDocID], [Name]
FROM Hierachy
--WHERE [Level] > 0

I got it! Here is the SQL that works:

WITH Hierachy([DocID], [ParentDocID], [Name], [Level])
AS
(
SELECT [DocID], [ParentDocID], [Name], 0 AS [Level]
FROM [Documents] d
WHERE (d.[DocID] = @ParentDocID) AND ([Folder] = 1) 
AND ([Status] = 'A') AND ([AppGroupID] = @AppGroupID)
UNION ALL
SELECT d.[DocID], d.[ParentDocID], d.[Name], dh.[Level] + 1
FROM [Documents] d
INNER JOIN Hierachy dh
ON dh.[ParentDocID] = d.[DocID]
WHERE ([Folder] = 1) 
AND ([Status] = 'A') AND ([AppGroupID] = @AppGroupID)
)
SELECT [DocID], [ParentDocID], [Name]
FROM Hierachy
ORDER BY [Level] DESC
)

Answer 1

Check below link you will get perfact answer for your question.

SQL Server: How to get all child records given a parent id in a self referencing table

Answer 2

Sure you can. You can use CURSOR or WHILE LOOP or XML. I have an example like you. Here's the WHILE LOOP with a temp Table, it selects parents of a node with a provided ID:

DECLARE @ID INT = 4
DECLARE @Parent_ID INT
DECLARE @Tree TABLE
(
    ID int,
    Value NVARCHAR(10),
    Parent_ID int
)

SELECT @Parent_ID = Parent_ID FROM Tree 
WHERE ID = @ID

WHILE @Parent_ID IS NOT NULL
BEGIN
    INSERT INTO @Tree
    SELECT * FROM Tree
    WHERE ID = @Parent_ID

    SELECT @Parent_ID = Parent_ID FROM Tree
    WHERE ID = @Parent_ID
END

SELECT * FROM @Tree

Answer 3

This describes solving a similar problem, ie walking up a tree. Any inline sql, such as this is best executed within a stored procedure. Solving it in SQL is probably the best approach, as you already have all the data there.