title: Merge the two xml fragments into one?
body: <p>How to merge the xml content of <code>@a</code> and <code>@b</code> into <code>@c</code>?</p>
  
  <pre><code>declare @a xml = (select 1 aaa for xml path('AAAs'));
  declare @b xml = (select 1 bb1, 2 bb2 for xml path('BBBs'));
  declare @c xml = ... @a + @b ....?
  </code></pre>
  
  <p>I need to pass the merged xml to a stored procedure.</p>
  
  <hr>
  
  <p>I know it's possible to cast the xml to varchar and concat them and convert it back to xml. Any better approach? The xml content can be big.</p>