Creating a recursive CTE with no rootrecord - sql-server

Question

My Apologies for the appalling Title, I was trying to be descriptive but not sure I got to the point. Hopefully the below will explain it
I begin with a table that has the following information
Party Id Party Name Party Code Parent Id
1 Acme 1 ACME1 1
2 Acme 2 ACME2 1
3 Acme 3 ACME3 3
4 Acme 4 ACME4 4
5 Acme 5 ACME5 4
6 Acme 6 ACME6 6
As you can see this isn't perfect for a recursive CTE because rather than having a NULL where there isn't a parent record it is instead parented to itself (see rows 1,3 and 6). Some however are parented normally.
I have therefore tried to amend this table in a CTE then refer to the output of that CTE as part of my recursive query... This doesn't appear to be running very well (no errors yet) so I wonder if I have managed to create an infinite loop or some other error that just slows the query to a crawl rather than killing it
My Code is below... please pick it apart!
--This is my attempt to 'clean' the data and set records parented to themselves as the 'anchor'
--record
WITH Parties
AS
(Select CASE
WHEN Cur_Parent_Id = Party_Id THEN NULL
ELSE Cur_Parent_Id
END AS Act_Parent_Id
, Party_Id
, CUR_PARTY_CODE
, CUR_PARTY_NAME
FROM EDW..TBDIMD_PARTIES
WHERE CUR_FLG = 1),
--In this CTE I referred to my 'clean' records from above and then traverse through them
--looking at the actual parent record identified
linkedParties
AS
(
Select Act_Parent_Id, Party_Id, CUR_PARTY_CODE, CUR_PARTY_NAME, 0 AS LEVEL
FROM Parties
WHERE Act_Parent_Id IS NULL
UNION ALL
Select p.Act_Parent_Id, p.Party_Id, p.CUR_PARTY_CODE, p.CUR_PARTY_NAME, Level + 1
FROM Parties p
inner join
linkedParties t on p.Act_Parent_Id = t.Party_Id
)
Select *
FROM linkedParties
Order By Level
From the data I supplied earlier the results I would expect are;
Party Id Party Name Party Code Parent Id Level
1 Acme 1 ACME1 1 0
3 Acme 3 ACME3 3 0
4 Acme 4 ACME4 4 0
6 Acme 6 ACME6 6 0
2 Acme 2 ACME2 1 1
5 Acme 5 ACME5 4 1
If everything seems to be OK then I'll assume its just a processing issue and start investigating that but I am not entirely comfortable with CTE's so wish to make sure the error is not mine before looking elsewhere.
Many Thanks

Answer 1

I think that you made it more complicated than it needs to be :).
drop table #temp
GO
select
*
into #temp
from (
select '1','Acme 1','ACME1','1' union all
select '2','Acme 2','ACME2','1' union all
select '3','Acme 3','ACME3','3' union all
select '4','Acme 4','ACME4','4' union all
select '5','Acme 5','ACME5','4' union all
select '6','Acme 6','ACME6','6'
) x ([Party Id],[Party Name],[Party Code],[Parent Id])
GO
;with cte as (
select
*,
[Level] = 0
from #temp
where 1=1
and [Party Id]=[Parent Id] --assuming these are root records
union all
select
t.*,
[Level] = c.[Level]+1
from #temp t
join cte c
on t.[Parent Id]=c.[Party Id]
where 1=1
and t.[Party Id]<>t.[Parent Id] --prevent matching root records with themselves creating infinite recursion
)
select
*
from cte
(* should ofcourse be replaced with actual column names)