title: Kusto KQL reference first object in an JSON array
body: <p>I need to grab the value of the first entry in a json array with Kusto KQL in Microsoft Defender ATP.</p>
  
  <p>The data format looks like this (anonymized), and I want the value of "UserName":</p>
  
  <pre><code>[{"UserName":"xyz","DomainName":"xyz","Sid":"xyz"}]
  </code></pre>
  
  <p>How do I split or in any other way get the "UserName" value?</p>