Loop and modify xml nodes SQL Server

Question

I want to loop through xml nodes in SQL Server, and create a copy of each node containing ','.

For example, for the following xml :

 declare @answerXML xml = '<answers><answer part="1">answer,test0</answer><answer part="1">answer,test1</answer></answers>'

I want to be modified to become the following :

declare @answerXML xml = '<answers><answer part="1">answer,test0</answer><answer part="1">answer, test0</answer><answer part="1">answer,test1</answer><answer part="1">answer, test1</answer></answers>'

(Each node is duplicated, and in the added node, a space is added after the comma).

I was planing in using something like this :

SELECT 
    T.ref.value('.', 'varchar(256)') AS Answer 
FROM 
    (SELECT 
         [Xml] = @answerXML.query('for $i in data(/answers/answer) 
                                   return element temp { $i }')
    ) A
CROSS APPLY
    A.Xml.nodes('/temp') T(ref) 

But no use, it seems it's too complicated.

Can anyone help in how to loop and update XML in T-SQL?

Thank you in advance,

Answer 1

You can try to shred the XML and rebuild it from scratch:

declare @answerXML xml=
'<answers>
  <answer part="1">answer,test0</answer>
  <answer part="1">answer,test1</answer>
</answers>';

SELECT a.value(N'@part',N'int') AS [answer/@part]
      ,a.value(N'text()[1]',N'nvarchar(max)') AS [answer] 
      ,''
      ,a.value(N'@part',N'int') AS [answer/@part]
      ,REPLACE(a.value(N'text()[1]',N'nvarchar(max)'),',',', ') AS [answer] 
FROM @answerXML.nodes(N'/answers/answer') AS A(a)
FOR XML PATH(''),ROOT('answers')

The result

<answers>
  <answer part="1">answer,test0</answer>
  <answer part="1">answer, test0</answer>
  <answer part="1">answer,test1</answer>
  <answer part="1">answer, test1</answer>
</answers>