Question

Is there some way to transform/project XML from an XML column in the select clause of an Sql Server query?

Lets say we have a table with Id:Guid , Data:XML .

And lets say we have the following data in the “Data” column:

<Order>
  <Details>
     <Detail>
         <Quantity>10</Quantity>
         <ItemPrice>20</Quantity>
     </Detail>
     <Detail>
         <Quantity>10</Quantity>
         <ItemPrice>20</Quantity>
     </Detail>
  </Details>
</Order> 

is there any way to project this (using a select + xquery) into , say for example:

<Order>
  <Details>
     <Detail>
         <LineTotal>200</LineTotal>
     </Detail>
     <Detail>
         <LineTotal>200</LineTotal>
     </Detail>
  </Details>
</Order> 

I’m not interested in how this can be done in memory of my app, I want a server side transform in the select clause in the sql query.

Answer 1

Produces exactly the output you want, but SQL Server XML is quite limited. In this example, you really need to know exactly how to (re)produce the entire tree – with the variation “hand coded”.

declare @tbl table (id uniqueidentifier, data xml)
insert @tbl select newid(), '
<Order>
  <Details>
     <Detail>
         <Quantity>10</Quantity>
         <ItemPrice>20</ItemPrice>
     </Detail>
     <Detail>
         <Quantity>10</Quantity>
         <ItemPrice>20</ItemPrice>
     </Detail>
  </Details>
</Order>'

select ((
    select d.d.value('(Quantity)[1]','int') * d.d.value('(ItemPrice)[1]','int') [LineTotal]
    from ds.ds.nodes('Detail') d(d)
    for xml path('Detail'), type)) Details
from @tbl t
cross apply data.nodes('Order/Details') ds(ds)
for xml path('Order')