Recursive CTE with multiple valid same parent child relationships - tsql

Question

I have an equipment inventory application I am working on. The piece of equipment is my top level and it contains assemblies, sub-assemblies and parts. I am trying to use recursive CTE to display the parent/child relationships. The issue I am having is that some assemblies can have multiple sub-assemblies that are the same, meaning there is not difference in the part numbers. This is causing my query to not show the correct relationship based on my order by statement. This is the first time I have used CTE so I have be using a lot learned on the web.
PartNumberID 174 is used twice in this assembly.
Sample Table
equipmentID parentPartNumberID partNumberID
17 1 281
17 281 156
17 156 161
17 161 224
17 281 174
17 174 192
17 192 56
17 174 193
17 281 174
17 174 192
17 192 56
17 174 193
17 281 283
17 ` 283 183
17 283 277
17 283 173
Results of Query
PARENT CHILD PARTLEVEL HIERARCHY
1 281 0 281
281 156 1 281.156
156 161 2 281.156.161
161 224 3 281.156.161.224
281 174 1 281.174
281 174 1 281.174
174 192 2 281.174.192
174 192 2 281.174.192
192 56 3 281.174.192.56
192 56 3 281.174.192.56
174 193 2 281.174.193
174 193 2 281.174.193
281 283 1 281.283
283 173 2 281.283.173
283 183 2 281.283.183
283 277 2 281.283.277
As you can see the hierarchy is created correctly but I it is not being returned correctly because there is nothing unique for these 2 assemblies for the order by statement.
The Code:
with parts(PARENT,CHILD,PARTLEVEL,HIERARCHY) as (select parentPartNumberID,
--- Used to get rid of duplicates
CASE WHEN ROW_NUMBER() OVER (PARTITION BY partNumberID ORDER BY partNumberID) > 1
THEN NULL
ELSE partNumberID END AS partNumberID,
0,
CAST( partNumberID as nvarchar) as PARTLEVEL
FROM db.tbl_ELEMENTS
WHERE parentPartNumberID=1 and equiptmentID=17
UNION ALL
SELECT part1.parentPartNumberId,
--- Used to get rid of duplicates
CASE WHEN ROW_NUMBER() OVER (PARTITION BY parts1.partNumberID ORDER BY parts1.partNumberID) > 1
THEN 10000 + parts1.partNumberID
ELSE parts1.partNumberID END,
PARTLEVEL+1,
cast(parts.hierarchy + '.' + CAST(parts1.partNumberID as nvarchar) as nvarchar)
from dbo.tbl_BOM_Elements as parts1 inner
join parts onparts1.parentPartNumberID=parts.CHILD
where id =17)
select CASE WHEN PARENT > 10000
THEN PARENT - 10000
ELSE PARENT END AS PARENT,
CASE WHEN CHILD > 10000
THEN CHILD - 10000
ELSE CHILD END AS CHILD,
PARTLEVEL,HIERARCHY
from parts
order by hierarchy
I tried to create a unique ID to order but was not successful. Any suggestions would be greatly appreciated.

Answer 1

I'll start by just answering the part about getting a sequential id.
If you have control you could just a unique Id to your source table. Having a surrogate primary key would be pretty typical here.
You could instead use a second CTE before the recursive one and add the row numbers there using ROW_NUMBER() OVER BY (ORDER BY equipmentID, parentPartNumberID, partNumberID). Then build your recursive CTE off of that rather than the source table directly.
Better might be to use the first CTE to instead GROUP BY equipmentID, parentPartNumberID, partNumberID and add a COUNT(1) field. This would let you instead use the count in you hierarchy rather than getting the duplicates. Something like 281.283.277x2 or whatever.