這裏是通過HIERARCHYID表示文件系統的一個示例:
/*
Setup:
- Create the table to hold the files
- nodeDepth is identifier of the depth for readability
- fullpath is the full path of the file or directory
- nodePath is the HierarchyID
- nodePath identifies the row within the tree
*/
DECLARE @t TABLE (
nodeID INT NOT NULL IDENTITY(1,1) PRIMARY KEY,
nodeDepth VARCHAR(10) NOT NULL,
fullPath VARCHAR(20) NOT NULL,
nodePath HIERARCHYID NOT NULL
)
負載數據:
/*
Load the nodePath value with the Parse command:
- The root node has a single/
- Every nodePath must begin and end with/
- /1/2/ the second item on level 2
*/
INSERT @t (fullPath, nodeDepth, nodePath) VALUES
('/','1',HIERARCHYID::Parse('/')),
('/dir1','1.1',HIERARCHYID::Parse('/1/1/')),
('/file1','1.2',HIERARCHYID::Parse('/1/2/')),
('/dir2','1.3',HIERARCHYID::Parse('/1/3/')),
('/dir2/dir3','1.3.1',HIERARCHYID::Parse('/1/3/1/')),
('/dir2/dir3/file2','1.3.1.1',HIERARCHYID::Parse('/1/3/1/1/'))
顯示的路徑:
SELECT *
FROM @t
nodeID nodeDepth fullPath nodePath
----------- ---------- -------------------- --------
1 1 / 0x
2 1.1 /dir1 0x5AC0
3 1.2 /file1 0x5B40
4 1.3 /dir2 0x5BC0
5 1.3.1 /dir2/dir3 0x5BD6
6 1.3.1.1 /dir2/dir3/file2 0x5BD6B0
獲取文件2的祖先(上一級):
SELECT *
FROM @t
WHERE nodePath =
(SELECT nodePath.GetAncestor(1)
FROM @t
WHERE fullPath = '/dir2/dir3/file2')
nodeID nodeDepth fullPath nodePath
----------- ---------- -------------------- ---------
5 1.3.1 /dir2/dir3 0x5BD6
獲取DIR2的所有descentants:
SELECT *
FROM @t
WHERE nodePath.IsDescendantOf(
(SELECT nodePath
FROM @t
WHERE fullPath = '/dir2')) = 1
AND fullPath <> '/dir2' /* Parent is considered its own descendant */
nodeID nodeDepth fullPath nodePath
----------- ---------- -------------------- --------
5 1.3.1 /dir2/dir3 0x5BD6
6 1.3.1.1 /dir2/dir3/file2 0x5BD6B0
獲取根路徑:
SELECT *
FROM @t
WHERE nodePath = HIERARCHYID::GetRoot()
nodeID nodeDepth fullPath nodePath
----------- ---------- -------------------- --------
1 1 / 0x
獲取等級升文件2的:
SELECT nodePath.GetLevel() AS level
FROM @t
WHERE fullPath = '/dir2/dir3/file2'
level
------
4
參考文獻:
您希望保留的表結構同步與文件怎麼辦系統?如果我在/ dir2中添加一個文件,表格應該多快知道它?立即,一些延遲,從來沒有?在運行時只讀目錄結構是否更有意義?這不會真的需要hierarchyid。 –
謝謝,我沒有試圖保持數據庫與文件系統同步。它基本上將作爲自己的文件系統(文件節點將指向磁盤上的文件,但不會有目錄結構)。我真正需要幫助的只是這一部分。謝謝。 – user8790899800
爲什麼@Aaron Bertrand的評論在不是真正相關的時候被上調了?似乎很奇怪。 – user8790899800