[英]Represent File System in DB (using hierarchyid in SQL Server 2008)
我没有找到任何具体的例子,但我有兴趣使用hierarchyid数据类型来表示具有更新等的整个目录结构。 这是为hierarchyid引用的常见用例,但我找不到构建这样一个示例的任何文章。
我只想表示一个完整的目录结构,例如:
/dir1
/file1
/dir2
/dir2/dir3
/dir2/dir3/file2
**我不是想与磁盘上的文件系统同步。 它纯粹通过数据库表示。 **
以下是通过hierarchyid表示文件系统的示例 :
/*
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
)
加载数据:
/*
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/'))
显示路径:
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
获取file2的祖先(上一层):
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
得到dir2的所有下降:
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
获取根路径:
SELECT *
FROM @t
WHERE nodePath = HIERARCHYID::GetRoot()
nodeID nodeDepth fullPath nodePath
----------- ---------- -------------------- --------
1 1 / 0x
获取file2的级别:
SELECT nodePath.GetLevel() AS level
FROM @t
WHERE fullPath = '/dir2/dir3/file2'
level
------
4
参考文献:
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