Question

How can the following statement best be modified so that I receive a list of Contact.Name with Address.Location (I’d like to use XPath and not subqueries/WHERE-conditions if possible)? I’ve tried all sorts of syntax at @@@Name but no luck 🙁 – I want to reference the original node there.

DECLARE @data AS XML
SELECT @data = '
    <Data>
        <Contact Name="John"/>
        <Contact Name="Bob"/>
        <Address ContactName="John" Location="JohnStreet1"/>
        <Address ContactName="John" Location="JohnStreet2"/>
        <Address ContactName="Bob" Location="BobStreet1"/>
    </Data> 
'

SELECT 
    x.v.value('@Name','VARCHAR(255)') [Contact.Name],   
    y.v.value('@Location','VARCHAR(255)') [Address.Location]
FROM 
    @data.nodes('/Data[1]/Contact') AS x(v)
CROSS APPLY
    x.v.nodes('/Data[1]/Address[@ContactName=@@@Name]') AS y(v)
ORDER BY
    x.v.value('@Name','VARCHAR(255)')

PS. This won’t work since the parameter needs to be a literal 🙁

x.v.nodes('/Data[1]/Address[@ContactName=' + x.v.value('@Name','VARCHAR(255)') + ']') AS y(v)

Please note: Currently I’m doing the following to get the desired resultset (but not in a clean XPath way):

SELECT 
    x.v.value('@Name','VARCHAR(255)') [Contact.Name],   
    y.v.value('@Location','VARCHAR(255)') [Address.Location]
FROM 
    @data.nodes('/Data[1]/Contact') AS x(v)
CROSS APPLY
    x.v.nodes('/Data[1]/Address') AS y(v)
WHERE
    y.v.value('@ContactName','VARCHAR(255)')=x.v.value('@Name','VARCHAR(255)')
ORDER BY
    x.v.value('@Name','VARCHAR(255)')

Answer 1

Here is a pure XQuery (which also happens to be a pure XPath 2.0 expression):

  for $c in /*/Contact/@Name
    return
      for $loc in /*/Address[@ContactName eq $c]/@Location
           return
              data(($c, $loc, '
'))

When this XPath expression is evaluated against the provided XML document:

<Data>
    <Contact Name="John"/>
    <Contact Name="Bob"/>
    <Address ContactName="John" Location="JohnStreet1"/>
    <Address ContactName="John" Location="JohnStreet2"/>
    <Address ContactName="Bob" Location="BobStreet1"/>
</Data>

the wanted, correct result is produced:

John JohnStreet1
 John JohnStreet2 
 Bob BobStreet1 

Do Note:

This is a pure XQuery / XPath 2.0 solution. I don’t know the SQL Server XQuery dialect and hope that you would be able to apply this solution to your case.

Probably something like:

select @data.query(
      'for $c in /*/Contact/@Name
        return
          for $loc in /*/Address[@ContactName eq $c]/@Location
               return
                  data(($c, $loc, "
"))'
                   )

Update:

As noted in a comment by Mikael Eriksson, SQL Server XQuery doesn’t accept “heterogeneous sequences” and raises an error.

Then this, slightly modified query works:

select @data.query(
      'for $c in /*/Contact/@Name
        return
          for $loc in /*/Address[@ContactName eq $c]/@Location
               return
                  (string($c), string($loc), "
")'

and produces the above wanted, correct result.