title: KQL show only matching results
body: <p>Ok so I have a query that looks like this:</p>
  <pre><code>        let event = Event
          | summarize by Computer;
          let heartbeat = Heartbeat 
          | where ResourceProvider == &quot;Microsoft.Compute&quot; or ComputerEnvironment == &quot;Azure&quot;
          | summarize by Computer;
          let total = union event, heartbeat;
          
  </code></pre>
  <p>The results of the event query and the heartbeat query are similar but I would like to see only the computers that show up in both queries.
  Is there a way to do that?</p>