如何在Sql Server 2000中用一条语句实现树的查询

以公司的网站栏目表为例，表结构（表名：Subject）如下：

字段名称	字段类型	字段长度
id	int	4
NAME	varchar	200
PARENTID	int	4
CODE	varchar	100

在数据库中创建一个自定义函数：

CREATE FUNCTION dbo.GetSubtreeInfo
( @manager_id AS char(5)
)
RETURNS @treeinfo table
( [id] [int] NOT NULL ,
[name] [varchar] (100) NOT NULL,
[parentid] [int] NOT NULL,
[code] [varchar] (100) NULL,
[levels] [int] NOT NULL
) AS
BEGIN
DECLARE @level AS int
SELECT @level = 0
INSERT INTO @treeinfo
SELECT [id], [name], [parentid], [code], @level
FROM [subject]
WHERE [id] = @manager_id
WHILE @@ROWCOUNT > 0
BEGIN
SET @level = @level + 1
INSERT INTO @treeinfo
SELECT E.[id], E.[name], E.[parentid], E.[code], @level
FROM [subject] AS E JOIN @treeinfo AS T
ON E.[parentid] = T.[id] AND T.[levels] = @level - 1
END
RETURN
END
说明：其中的levels是树状结构的级数
使用方法：select SPACE(levels*3)+name ,* from GetSubtreeInfo(973) 其中973可以修改为你要开始查询的起始节点