title: XQuery: how to properly append , in for loop
body: <p>So I have xml data like this:</p>
  
  <pre><code>  &lt;PhoneNumber&gt;213-512-7457&lt;/PhoneNumber&gt;
    &lt;PhoneNumber&gt;213-512-7465&lt;/PhoneNumber&gt;
  </code></pre>
  
  <p>and with this XQuery:</p>
  
  <pre><code>&lt;PhoneNumberList&gt;
  {
    for $phone in $c//PhoneNumber
    let $phoneStr := ""
    return concat($phoneStr, $phone) 
  }
  &lt;/PhoneNumberList&gt;
  </code></pre>
  
  <p>I get:</p>
  
  <pre><code>&lt;PhoneNumberList&gt;213-512-7457213-512-7465&lt;/PhoneNumberList&gt;
  </code></pre>
  
  <p>But I actually want:</p>
  
  <pre><code>&lt;PhoneNumberList&gt;213-512-7457, 213-512-7465&lt;/PhoneNumberList&gt;
  </code></pre>
  
  <p>Could someone shed some light on how to do this?</p>