sqlserver2005中的分层查询

我在SQLServer2005中的一个表中有一个数据结构，表示一个相关对象链。每个对象可以在许多步骤中进行替换。我想执行一个查询，返回替换链中的所有对象和每个对象的叶

数据：

id  replacement
1   null
2   3
3   null
4   5
5   6
6   null

结果应该是：

id  replacement
1   null
2   3
3   null
4   6
5   6
6   null

我相信递归CTE是一个很好的方法，但我不能对它掉以轻心。这个问题的一个限制是我无法更改数据结构，因为数据库不在我的控制范围内。

看看这个

DECLARE @Table TABLE(
        ID INT,
        ReplacementID INT
)

INSERT INTO @Table (ID,ReplacementID) SELECT 1, NULL
INSERT INTO @Table (ID,ReplacementID) SELECT 2, 3
INSERT INTO @Table (ID,ReplacementID) SELECT 3, NULL
INSERT INTO @Table (ID,ReplacementID) SELECT 4, 5
INSERT INTO @Table (ID,ReplacementID) SELECT 5, 6
INSERT INTO @Table (ID,ReplacementID) SELECT 6, NULL

INSERT INTO @Table (ID,ReplacementID) SELECT 7, 8
INSERT INTO @Table (ID,ReplacementID) SELECT 8, 9
INSERT INTO @Table (ID,ReplacementID) SELECT 9, 10
INSERT INTO @Table (ID,ReplacementID) SELECT 10, NULL

SELECT * FROM @Table

;WITH repl AS (
    SELECT  *, 1 AS Depth
    FROM    @Table t
    UNION   ALL
    SELECT  r.ID,
            t.ReplacementID,
            r.Depth + 1
    FROM    repl r INNER JOIN
            @Table t ON r.ReplacementID = t.ID
    WHERE   t.ReplacementID IS NOT NULL
)
SELECT  repl.ID,
        repl.ReplacementID
FROM    (
            SELECT  ID,
                    MAX(Depth) Depth
            FROM    repl
            GROUP BY ID
        ) Depths INNER JOIN
        repl    ON  Depths.ID = repl.ID
                AND Depths.Depth = repl.Depth
ORDER BY 1

看看这个

DECLARE @Table TABLE(
        ID INT,
        ReplacementID INT
)

INSERT INTO @Table (ID,ReplacementID) SELECT 1, NULL
INSERT INTO @Table (ID,ReplacementID) SELECT 2, 3
INSERT INTO @Table (ID,ReplacementID) SELECT 3, NULL
INSERT INTO @Table (ID,ReplacementID) SELECT 4, 5
INSERT INTO @Table (ID,ReplacementID) SELECT 5, 6
INSERT INTO @Table (ID,ReplacementID) SELECT 6, NULL

INSERT INTO @Table (ID,ReplacementID) SELECT 7, 8
INSERT INTO @Table (ID,ReplacementID) SELECT 8, 9
INSERT INTO @Table (ID,ReplacementID) SELECT 9, 10
INSERT INTO @Table (ID,ReplacementID) SELECT 10, NULL

SELECT * FROM @Table

;WITH repl AS (
    SELECT  *, 1 AS Depth
    FROM    @Table t
    UNION   ALL
    SELECT  r.ID,
            t.ReplacementID,
            r.Depth + 1
    FROM    repl r INNER JOIN
            @Table t ON r.ReplacementID = t.ID
    WHERE   t.ReplacementID IS NOT NULL
)
SELECT  repl.ID,
        repl.ReplacementID
FROM    (
            SELECT  ID,
                    MAX(Depth) Depth
            FROM    repl
            GROUP BY ID
        ) Depths INNER JOIN
        repl    ON  Depths.ID = repl.ID
                AND Depths.Depth = repl.Depth
ORDER BY 1