SQL Server “FOR XML” output from queries joining two tables

Question

I'm new to the "FOR XML" feature in SQL Server. I am using SQL Server 2012.

I have two tables, Word and Word_Expansion.

Sample data:

table [Word]:

WordOID   Word
-------   ----    
      1   PIPE
      2   WIRE

table [Word_Expansion]:

WEOID  fk_WordOID  Word_Expansion
-----  ----------  --------------
    1          2             COAX
    2          2    SPEAKER CABLE
    3          1          CONDUIT

Now, I would like to produce XML something like:

<expansion>
  <sub>WIRE</sub>
  <sub>SPEAKER CABLE</sub>
</expansion>
<expansion>
  <sub>PIPE</sub>
  <sub>CONDUIT</sub>
</expansion>

I have come close with various efforts at crafting XML FOR statements, but I just can't seem to grasp what it is that I need to do to get these two tables mashed into the right XML output. I'll be digging further into XML FOR syntax, but if you have a moment and know this well...

Does anyone have any pointers as to what I should try?

Answer 1

This should do the trick for you:

SQL:

SELECT Word Sub,      
        (      
             SELECT Word_Expansion  AS Sub   
             FROM Word_Expansion WE
             WHERE WE.fk_WordOID = W.WordOID 
             FOR XML PATH(''), type 
        )      
FROM Word W
FOR XML PATH ('Expansion')   

XML Output:

<Expansion>
  <Sub>Pipe</Sub>
  <Sub>CONDUIT</Sub>
</Expansion>
<Expansion>
  <Sub>Wire</Sub>
  <Sub>COAX</Sub>
  <Sub>SPEAKER CABLE</Sub>
</Expansion>

Although i'm not sure why you want Word.Word to be classified as "Sub"? Shouldn't this instead be the parent of Word_Expansion (which should be sub?)

EDIT: I found this link quite useful when looking into FOR XML and nested queries Nested FOR XML

Answer 2

Here is mine... I upvoted the first post because his was fastest, but it does it a little different so I figured it couldn't hurt to add mine...

With    groupedWords
As
(
        Select  WordOID, 
                Word
        From    Word
        Union   
        Select  fk_WordOID, Word_Expansion
        From    Word_Expansion
)
Select (Select  s.word As sub 
        From    groupedWords s 
        Where   s.WordOID = n.WordOID 
        For     Xml Path(''), Type)
From    groupedWords n
Group   By n.WordOID
For     Xml Path('expansion')