Finding node order in XML document in SQL Server

Question

How can I find the order of nodes in an XML document?

What I have is a document like this:

Answer 1

SQL Server's row_number() actually accepts an xml-nodes column to order by. Combined with a recursive CTE you can do this:

declare @Xml xml = 
'
    
        
    
    
        
            
            
        
    
'

;with recur as (
    select
        ordr        = row_number() over(order by x.ml),
        parent_code = cast('' as varchar(255)),
        code        = x.ml.value('@code', 'varchar(255)'),
        children    = x.ml.query('./value')
    from @Xml.nodes('value') x(ml)
    union all
    select
        ordr        = row_number() over(order by x.ml),
        parent_code = recur.code,
        code        = x.ml.value('@code', 'varchar(255)'),
        children    = x.ml.query('./value')
    from recur
    cross apply recur.children.nodes('value') x(ml)
)
select *
from recur
where parent_code = '121'
order by ordr

As an aside, you can do this and it'll do what do you expect:

select x.ml.query('.')
from @Xml.nodes('value/value')x(ml)
order by row_number() over (order by x.ml)

Why, if this works, you can't just order by x.ml directly without row_number() over is beyond me.