WITH no1 AS(
SELECT a.benji AS zong ,b.* FROM dengji a INNER JOIN dengji b
ON a.benji=b.shangji AND a.benji IN (SELECT shangji FROM dengji)
),
no3 AS(
SELECT x.zong,y.benji,y.shangji FROM no1 x INNER JOIN no1 y on x.benji=y.shangji OR x.zong=y.shangji
UNION ALL
SELECT m.zong,n.benji,n.shangji FROM no3 m INNER JOIN no1 n on m.benji=n.shangji
)
SELECT * FROM no3 WHERE zong=3 GROUP BY ZONG,BENJI,SHANGJI

CREATE TABLE [dbo].[dengji](
[benji] [int] IDENTITY(1,1) NOT NULL,
[shangji] [int] NULL
) ON [PRIMARY]