Recursive CTE with tree hierarchy SQL Server - sql-server

Question

I need to use recursive with SQL Server, but i don't know how use it with my hierarchy tree.
I need some help for creating my query and know if it's possible with CTE Recursion.
My example :
I have two tables : piece (piece_id) and piece_equivalence(piece1_id, piece2_id)
First, i need to get all the piece from the first table :
SELECT DISTINCT p.record_id FROM piece p
Secondly, i need to check if the piece exists in the second table (piece1_id or piece2_id)
SELECT DISTINCT p.record_id
FROM piece p
inner join piece_equivalence pe
ON (pe.piece1_id = p.record_id OR pe.piece2_id = p.record_id)
Thirdly, if the piece exist, I need to check the piece1_id or piece2_id. This ID can have an equivalence too.
So I will check the second step too with my piece1_id or piece2_id.
Currently I did recursive calling the same function with parameter piece1 or piece2.
Graphical view with nodes :
piece_id
___/ \___
/ \
table : piece_equivalence piece1_id or piece2_id piece1_id or piece2_id
/ \ / \
table : piece_equivalence piece1_id or piece2_id same same same
Graphical with letters :
A
___/ \___ ________
/ \ \
B C D
/ \ / \ / \
D E F B E G
/ /
G H
A : piece
B, C, D, E, F, G, H are equivalences.
WARNING : I need to stock all piece with their equivalence in a temp table. For avoiding duplicate entry or infinity loop we must check this temp table the data exists or not.
EDIT :
I did this :
WITH pieces_CTE
AS
(
SELECT TOP 1 p.record_id as parent,
case when pe.piece1_id <> p.record_id then pe.piece1_id else pe.piece2_id end as enfant,
1 as level
FROM piece p
inner join piece_equivalence pe ON (pe.piece1_id = p.record_id OR pe.piece2_id = p.record_id) AND pe.pertinence = 100
AND pe.piece1_id <> pe.piece2_id
UNION ALL
SELECT c.parent, case when enfant.piece1_id <> c.parent then enfant.piece1_id else enfant.piece2_id end as enfant,
c.level+1
from pieces_CTE c
INNER JOIN piece_equivalence enfant ON (enfant.piece1_id = c.parent OR enfant.piece2_id = c.parent)
WHERE enfant.pertinence = 100
)
SELECT * from pieces_CTE ORDER BY parent,level,enfant
OPTION (MAXRECURSION 32767)
The statement terminated. The maximum recursion 100 has been exhausted
before statement completion.
But I have a large record on it, and my query has to much records, I think it's impossible to use CTE with many redundant cycles...
But why I have the same error with TOP 1 ?

Answer 1

Before you start with the Recursive CTE, You need to Know Few Things
You can't use DISTINCT or UNION
You Can't Use LEFT JOIN in the Recursive part of the CTE
You need to make sure the Recursion does not end in a Dead Lock. Otherwise by the Default Recursion count of 100, the CTE Will Terminate. Please see the below Example :
DECLARE #MyData TABLE (
SeqNo INT IDENTITY(1,1),
FullName VARCHAR(50),
ManagerId INT )
INSERT INTO #MyData (
FullName ) VALUES('CEO')
--Insert Sub Components
INSERT INTO #MyData (
FullName,
ManagerId ) SELECT
'Department Head 1',
ManagerId = SeqNo
FROM #MyData
WHERE FullName = 'CEO' UNION SELECT
'Department Head 2',
ManagerId = SeqNo
FROM #MyData
WHERE FullName = 'CEO' UNION SELECT
'Department Head 3',
ManagerId = SeqNo
FROM #MyData
WHERE FullName = 'CEO'
INSERT INTO #MyData (
FullName,
ManagerId ) SELECT
'Manager 1',
ManagerId = SeqNo
FROM #MyData
WHERE FullName = 'Department Head 1' UNION SELECT
'Manager 2',
ManagerId = SeqNo
FROM #MyData
WHERE FullName = 'Department Head 1' UNION SELECT
'Manager 3',
ManagerId = SeqNo
FROM #MyData
WHERE FullName = 'Department Head 3'
;WITH CTE AS (
SELECT
SeqNo,
FullName,
Manager = ISNULL(FullName,'')
FROM #MyData
WHERE ManagerId IS NULL
UNION ALL
SELECT
MD.SeqNo,
MD.FullName,
Manager = ISNULL(CTE.FullName,'')
FROM CTE
INNER JOIN #MyData MD
ON CTE.SeqNo = MD.ManagerId ) SELECT
*
FROM CTE
SeqNo FullName Manager
----------- -------------------------------------------------- --------------------------------------------------
1 CEO CEO
2 Department Head 1 CEO
3 Department Head 2 CEO
4 Department Head 3 CEO
7 Manager 3 Department Head 3
5 Manager 1 Department Head 1
6 Manager 2 Department Head 1