Nhiều cây cha mẹ (hoặc digraph) triển khai sql server 2005

Chà, cuối cùng tôi đã nghĩ ra giải pháp sau đây, đó là cách mà tôi tìm ra để hỗ trợ các cây nhiều rễ và cũng như các con số quay vòng.

create table #ObjectRelations
(
    Id varchar(20),
    NextId varchar(20)
)

/* Cycle */
/*
insert into #ObjectRelations values ('A', 'B')
insert into #ObjectRelations values ('B', 'C') 
insert into #ObjectRelations values ('C', 'A')
*/

/* Multi root */

insert into #ObjectRelations values ('G', 'B')
insert into #ObjectRelations values ('A', 'B') 
insert into #ObjectRelations values ('B', 'C')
insert into #ObjectRelations values ('B', 'X')
insert into #ObjectRelations values ('C', 'E') 
insert into #ObjectRelations values ('C', 'D') 
insert into #ObjectRelations values ('E', 'F') 
insert into #ObjectRelations values ('D', 'F') 


declare @startIds table
(
    Id varchar(20) primary key
)

;WITH 
    Ids (Id) AS
    (
        SELECT  Id
        FROM    #ObjectRelations
    ),
    NextIds (Id) AS
    (
        SELECT  NextId
        FROM    #ObjectRelations
    )
INSERT INTO @startIds
/* This select will not return anything since there are not objects without predecessor, because it's a cyclic of course */
SELECT DISTINCT
    Ids.Id
FROM
    Ids
LEFT JOIN
    NextIds on Ids.Id = NextIds.Id
WHERE
    NextIds.Id IS NULL
UNION
/* So let's just pick anyone. (the way I will be getting the starting object for a cyclic doesn't matter for the regarding problem)*/
SELECT TOP 1 Id FROM Ids

;WITH Objects (Id, NextId, [Level], Way) AS
( -- This is the 'Anchor' or starting point of the recursive query
  SELECT rel.Id,
         rel.NextId,
         1,
         CAST(rel.Id as VARCHAR(MAX))
    FROM #ObjectRelations rel
   WHERE rel.Id IN (SELECT Id FROM @startIds)

   UNION ALL -- This is the recursive portion of the query

  SELECT rel.Id,
         rel.NextId,
         [Level] + 1,
         RecObjects.Way + ', ' + rel.Id
    FROM #ObjectRelations rel
   INNER JOIN Objects RecObjects -- Note the reference to CTE table name (Recursive Join)
      ON rel.Id = RecObjects.NextId
   WHERE RecObjects.Way NOT LIKE '%' + rel.Id + '%'

)
SELECT  DISTINCT 
        Id,
        NextId,
        [Level]
FROM    Objects
ORDER BY [Level]

drop table #ObjectRelations

Có thể hữu ích cho ai đó. Nó là dành cho tôi =PThanks