如何使用 SQL-Server 2000 查询层次信息? [英] How to query hierarchical information with SQL-Server 2000?

问题描述

我有一个表 Folders 包含有关文件夹的层次结构信息:

I've got a table Folders with hierarchical information about folders:

FolderID     FolderName     ParentID
1            Folder1        0
2            Folder2        1
3            Folder3        2
4            Folder4        3

对于 Folder4 我想以下列格式获取父文件夹:

For Folder4 I would like to get the parent folders in the following format:

Folder1\Folder2\Folder3\

<小时>

注意:我在之前问过这个问题，但我不能使用 CTE，因为我使用的是 SQL-Server 2000.

---

Note: I have asked this before, but I cannot use CTE because I am using SQL-Server 2000.

推荐答案

我已经编写了一个 SQL 函数，它应该返回您正在寻找的内容.

I've written a SQL function that should return what you're looking for.

/* Set up test data */
create table Folders (
    FolderID int,
    FolderName varchar(10),
    ParentID int
)

insert into Folders
    (FolderID, FolderName, ParentID)
    select 1,'Folder1',0 union all
    select 2,'Folder2',1 union all
    select 3,'Folder3',2 union all
    select 4,'Folder4',3        
go

/* Create function */
create function dbo.CreateFolderPath (@FolderID int)
returns varchar(1000)
as
begin
    declare @ParentID int
    declare @FolderPath varchar(1000)
    set @FolderPath = ''

    select @ParentID = ParentID
        from Folders
        where FolderID = @FolderID

    while @ParentID<>0 begin
        select @FolderPath = FolderName + '\' + @FolderPath, @ParentID = ParentID
            from Folders
            where FolderID = @ParentID
    end /* while */

    return @FolderPath
end /* function */
go

/* Demo the function */
select dbo.CreateFolderPath(4)

/* Clean up after demo */
drop function dbo.CreateFolderPath
drop table Folders

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