Prova qualcosa del genere:usa FOR XML PATH
e subselects per creare i sottonodi "collegati" per un determinato cliente (L'ho limitato a due sottotabelle - ma dovresti ottenerne l'"essenza" ed essere in grado di estenderlo a qualsiasi numero di sottotabelle collegate ):
SELECT
CustomerID AS '@CustomerID',
CustName AS '@Name',
(SELECT ProductName AS '@productname'
FROM dbo.Products p
WHERE p.CustomerID = c.CustomerID
FOR XML PATH('Product'), TYPE) AS 'Products',
(SELECT HobbyName AS '@hobbyname'
FROM dbo.Hobbies h
WHERE h.CUstomerID = c.CustomerID
FOR XML PATH('Hobby'), TYPE) AS 'Hobbies'
FROM
dbo.Customers c
FOR XML PATH('Customer'), ROOT('Customers')
Mi dà un output simile a:
<Customers>
<Customer CustomerID="1" Name="Fred">
<Products>
<Product productname="Table" />
<Product productname="Wardrobe" />
<Product productname="Chair" />
</Products>
<Hobbies>
<Hobby hobbyname="Golf" />
<Hobby hobbyname="Swimming" />
</Hobbies>
</Customer>
<Customer CustomerID="2" Name="Sue">
<Products>
<Product productname="CD Player" />
<Product productname="Picture frame" />
</Products>
<Hobbies>
<Hobby hobbyname="Dancing" />
<Hobby hobbyname="Gardening" />
<Hobby hobbyname="Reading" />
</Hobbies>
</Customer>
</Customers>