Recursive hierarchical traversal in MSSQL - sql-server

Question

Using MSSQL, I am trying to traverse through a table with parent child relationship. I need my result set so that I get all elements in a proper indented manner, till the last leaf, like shown below.
A parent item 36 has 2 children 17 and 18. Each of those children 17 and 18 have one more children to them 26, 42 respectively
36 - 17
17 - 26
36 - 18
18 - 42
But my recursion is working OK in terms of the data traversal, but order wise, it is failing. My recursive query gives me the following output
36 - 17
36 - 18
17 - 26
18 - 42
It brings all levels at once, stores them in a record, then traverses through each of the children of those levels.
Oracle's "connect by prior" seems to be working fine, but, MSSQL is not. I am pasting a sample of what I am using
WITH SRC (Level, PARITEMID, CHIITEMID) AS
(
SELECT
0 as Level,
PI.pitem_id as PARITEMID,
CI.pitem_id as CHIITEMID
FROM PI, CI JOIN <Condition> where PI.PITEM_ID =
UNION ALL
SELECT
Level + 1,
PI1.pitem_id as PARITEMID,
CI1.pitem_id AS CHIITEMID
FROM PI1, CI1 JOIN <Condition>
)
Select * from SRC
Is there something I need to do on the SRC I obtain by ordering it, or is there fundamentally something wrong with the recursion itself?

Answer 1

Wasn't clear on your field names so I assumed the following:
cItem_ID - Child ID
pItem_ID - Parent ID
item_Title - Item name/Description
Also, not clear on the Sequence, So I assumed Item_Title (alphabetical). However, you can use any field available. (see the the "10000+Row_Number()" lines)
I should note, cteR1, and cteR2 are not necessary. I do like the range keys, they server many purposes. If you do remove them, just set the final Order By to Order By A.Seq
Declare #MyTable table (pItem_ID int,cItem_ID int,item_Title varchar(50))
Insert into #MyTable values
(null,36,'Item 36')
,(36,17,'Item 17')
,(17,26,'Item 26')
,(36,18,'Item 18')
,(18,42,'Item 42')
Declare #Top int = null --<< Sets top of Hier Try 7
Declare #Nest varchar(25) = '|-----' --<< Optional: Added for readability
;with cteP as (
Select Seq = cast(10000+Row_Number() over (Order by item_Title) as varchar(500))
,cItem_ID
,pItem_ID
,Lvl=1
,item_Title
From #MyTable
Where IsNull(#Top,-1) = case when #Top is null then isnull(pItem_ID,-1) else cItem_ID end
Union All
Select Seq = cast(concat(p.Seq,'.',10000+Row_Number() over (Order by r.item_Title)) as varchar(500))
,r.cItem_ID
,r.pItem_ID
,p.Lvl+1
,r.item_Title
From #MyTable r
Join cteP p on r.pItem_ID = p.cItem_ID)
,cteR1 as (Select *,R1=Row_Number() over (Order By Seq) From cteP)
,cteR2 as (Select A.Seq,A.cItem_ID,R2=Max(B.R1) From cteR1 A Join cteR1 B on (B.Seq like A.Seq+'%') Group By A.Seq,A.cItem_ID )
Select A.R1
,B.R2
,A.cItem_ID
,A.pItem_ID
,A.Lvl
,item_Title = Replicate(#Nest,A.Lvl-1) + A.item_Title
From cteR1 A
Join cteR2 B on A.cItem_ID=B.cItem_ID
Order By A.R1
Returns