如何用SQL-Server 2000查詢分層信息？

Question

我有一個表Folders與層次信息有關文件夾：

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

對於Folder4我想獲得在以下格式的父文件夾：

Folder1\Folder2\Folder3\ 

---

注：我問過這個before，但是我不能使用CTE，因爲我正在使用SQL-Server 2000.

Answer 1

我寫了一個SQL函數，應該返回你正在尋找的東西。

/* 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