title: Linq to Sql is null in Where clause
body: <p>Is it possible to ignore Where clause if Sessions.Current.AdminProductId is null? I would like to optimize code below into one line of code.</p>
  
  <pre><code>if (Sessions.Current.AdminProductId == null)
    gvUsers.DataSource = DataAccess.Instance.Users;
  else
    gvUsers.DataSource = DataAccess.Instance.Users.Where(p =&gt; p.Orders.Any(o =&gt; o.ProductId == Sessions.Current.AdminProductId));
  </code></pre>