title: Linq to select parent records without children
body: <p>I have a hierarchy as such:</p>
  
  <pre><code>- Order
    - order details
        - work order header
           - work order details
  </code></pre>
  
  <p>I want to select work order headers that have no work order details.</p>
  
  <p>I have this so far, but it returns one level up, the order details...I want the next level down, work order headers.</p>
  
  <pre><code>IEnumerable&lt;OrderDetail&gt; odWithoutWoDtls = order.OrderDetails.Where(od =&gt; od.WorkOrderHeaders.Any(woh =&gt; woh.WorkOrderDetails.Count() == 0));
  </code></pre>