Regarde ça
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
