SYBASE: CONSOLIDATE Multiple rows into comma separated field

CREATE TABLE #tbl (ad_id INT, ac_id VARCHAR(255), dt INT, rel INT)

INSERT INTO #tbl VALUES (1,'10',111,1)

INSERT INTO #tbl VALUES (2,'11',112,0)

INSERT INTO #tbl VALUES (3,'12',113,0)

INSERT INTO #tbl VALUES (3,'13',114,1)

INSERT INTO #tbl VALUES (3,'14',115,1)

INSERT INTO #tbl VALUES (4,'15',116,1)

INSERT INTO #tbl VALUES (4,'16',117,1)

INSERT INTO #tbl VALUES (4,'17',118,1)

SELECT * , dt1 = MIN(dt), flg = 0

INTO #tbl2

FROM #tbl

WHERE rel = 1

GROUP BY ad_id

HAVING rel = 1

UPDATE #tbl2

        SET flg = 1

    FROM #tbl2

    WHERE dt = dt1

WHILE EXISTS (SELECT 1 FROM #tbl2

            WHERE  flg = 0)

BEGIN

    UPDATE #tbl2

            SET ac_id = t1.ac_id +',' + t2.ac_id

                ,flg = 2

        FROM #tbl2 t1, #tbl2 t2

        WHERE t1.ad_id = t2.ad_id

        AND t1.dt = t1.dt1

        AND t2.dt = (SELECT MIN(dt) FROM #tbl2

                        WHERE ad_id = t1.ad_id

                        AND dt > t1.dt)

    DELETE #tbl2

        FROM #tbl2 t1

        WHERE t1.dt = (SELECT MIN(dt) FROM #tbl2

                        WHERE ad_id = t1.ad_id

                        AND dt > t1.dt1)

END           

SELECT * FROM #tbl2