SQL Server 2005 recursive query with loops in data - is it possible?

Question

I\'ve got a standard boss/subordinate employee table. I need to select a boss (specified by ID) and all his subordinates (and their subrodinates, etc). Unfortunately the rea

Answer 1

this will work for the initial recursive link, but might not work for longer links

DECLARE @Table TABLE(
        ID INT,
        PARENTID INT
)

INSERT INTO @Table (ID,PARENTID) SELECT 1, 2

INSERT INTO @Table (ID,PARENTID) SELECT 2, 1

INSERT INTO @Table (ID,PARENTID) SELECT 3, 1

INSERT INTO @Table (ID,PARENTID) SELECT 4, 3

INSERT INTO @Table (ID,PARENTID) SELECT 5, 2


SELECT * FROM @Table

DECLARE @ID INT

SELECT @ID = 1

;WITH boss (ID,PARENTID) AS (
    SELECT  ID,
            PARENTID
    FROM    @Table
    WHERE   PARENTID = @ID
),
 bossChild (ID,PARENTID) AS (
    SELECT  ID,
            PARENTID
    FROM    boss
    UNION ALL
    SELECT  t.ID,
            t.PARENTID
    FROM    @Table t INNER JOIN
            bossChild b ON t.PARENTID = b.ID
    WHERE   t.ID NOT IN (SELECT PARENTID FROM boss)
)
SELECT  *
FROM    bossChild
OPTION (MAXRECURSION 0)

what i would recomend is to use a while loop, and only insert links into temp table if the id does not already exist, thus removing endless loops.