title: How to detect if app is installed based on upgrade code
body: <p>I am doing an installation of several products, but because they are built automatically in daily build, they have various GUIDs. They just have same UPGRADE code...</p>
  
  <p>So my question is:
  Is it possible to know just with UPGRADE code if the product is installed (without using own custom actions)?</p>
  
  <p>I was trying:</p>
  
  <pre><code>    &lt;Property Id="WF_INSTALLED" Value="NOT INSTALLED"&gt;
          &lt;ProductSearch Minimum="0" UpgradeCode="{XXXXXXXX-XXXX-XXXX-XXXX-8660911C6596}"/&gt;
      &lt;/Property&gt;
  </code></pre>
  
  <p>But it seems that I cannot use that... Also I find a registry record:</p>
  
  <pre><code>Root='HKLM' Key='SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UpgradeCodes\XXXXXXX'
  </code></pre>
  
  <p>where XXXXXXX is transformed UPGRADE Code, but there are no values under this key so I cannot check for its existence :(</p>
  
  <p>Any help will be appreciated.</p>
  
  <p><strong>EDIT:</strong> I am trying to discover if some other product is installed, not that one what I am currently installing. </p>