Using TSQL to generate XML

Question

I am trying to generate some XML using TSQL and having some trouble, I was able to get to traverse 2 levels but getting stuck at 3. How it should work in the example I have posted you have to Purchase Orders, the first purchase order only has one part with one release for that part. The second Purchase order as 2 parts each part with its own release. At the end I should have 2 XML documents that traverse 3 levels, release/part/purchase order. I think I am getting confused when linking to the next stage up as well as the group by.The example only shows 2 parts but there can be many parts to one purchase order but only ever one release per part, any help would be much appreciated.

DECLARE @sdv AS TABLE    
(
PID INT IDENTITY(1,1) PRIMARY KEY,
PurchaseOrder varchar(20),
PartNo int,
Release int
)


INSERT INTO @sdv values ('PURC123', 111, 1)
INSERT INTO @sdv values ('PURC333', 222, 1)
INSERT INTO @sdv values ('PURC333', 333, 1)


select 
    PurchaseOrder,
(
select
    PartNo,
(
select
    Release
from
@sdv a3
where 
a3.Release = a2.Release and
a3.PartNo = a2.PartNo and 
a3.PurchaseOrder = a1.PurchaseOrder
for xml path('Release'), type
) 
from 
@sdv a2
where 
a2.PartNo = a1.PartNo
group by a2.PartNo
for xml path('part'), type
) from @sdv a1
group by PurchaseOrder
for xml path('Purchase')

Answer 1

I am going to shoot you an answer so you can play around with it. I am around for a little bit longer today, but will check back tomorrow.

For this example I just used attributes as I can read it a bit easier. I did my grouping using a CTE and assumed the relationship was 1 to many between a part and a release. (could be wrong there, but need info from you). Was also a bit hazy about the levels needing to go a third deep. If we are talking about iterations of parts (versions) then you could simple add a @Release to the second level. Note: If you don't want attributes just remove the @before each of the tags.

I would highly recommend being very diligent about your code format whenever doing hierarchical xml work. Its easy to get lost.

CODE

DECLARE @sdv AS TABLE    
(
PID INT IDENTITY(1,1) PRIMARY KEY,
PurchaseOrder varchar(20),
PartNo int,
Release int
)


INSERT INTO @sdv values ('PURC123', 111, 1)
INSERT INTO @sdv values ('PURC333', 222, 1)
INSERT INTO @sdv values ('PURC333', 333, 1)

;WITH PO AS (
    SELECT  DISTINCT PurchaseOrder
    FROM    @sdv
)
SELECT  L1.PurchaseOrder AS "@PurchseOrder",
        (   SELECT  PartNo AS "@PartNo",
                    (   SELECT  DISTINCT L3.Release AS "@Release"
                        FROM    @sdv AS L3
                        WHERE   L2.PartNo = L3.PartNo
                        ORDER   BY L3.Release ASC
                        FOR     XML PATH('RELEASE'),TYPE
                    )
            FROM    @sdv AS L2
            WHERE   L2.PurchaseOrder = L1.PurchaseOrder
            FOR XML PATH('PART'), TYPE
        )       
FROM    PO AS L1
FOR     XML PATH('PurchaseOrder'), ROOT('PurchaseOrders')

XML OUTPUT

<PurchaseOrders>
  <PurchaseOrder PurchseOrder="PURC123">
    <PART PartNo="111">
      <RELEASE Release="1" />
    </PART>
  </PurchaseOrder>
  <PurchaseOrder PurchseOrder="PURC333">
    <PART PartNo="222">
      <RELEASE Release="1" />
    </PART>
    <PART PartNo="333">
      <RELEASE Release="1" />
    </PART>
  </PurchaseOrder>
</PurchaseOrders>