Question

I have an XML valued column that has multiple “parent” nodes. I need to insert a “child” node into each parent node. If I use

UPDATE mytable SET mycolumn.modify('insert <child/> into (//parent)[1]')

, then I’m inserting a child node into the first parent only.

How do I insert a child in every parent with a single query?

Answer 1

I believe the easiest way to accomplish this is to reconstruct the XML with a SELECT statement using CROSS APPLY and FOR XML.

Here’s an example, hope it makes sense. With this approach, you could also JOIN to another table for the data you want to insert into the <child2 /> node making this solution quite flexible.

DECLARE @t TABLE ( Document XML )
INSERT INTO @t
SELECT '<root><parent><child1>first row data</child1></parent><parent><child1>second row data</child1></parent></root>'

SELECT
    ref.value('child1[1]', 'varchar(max)') as child1, 
    'something to insert' as child2
FROM @t CROSS APPLY Document.nodes('//parent') R(ref)
FOR XML PATH('parent'), ROOT('root')

Results

<root>
  <parent>
    <child1>first row data</child1>
    <child2>something to insert</child2>
  </parent>
  <parent>
    <child1>second row data</child1>
    <child2>something to insert</child2>
  </parent>
</root>