title: NHibernate ISession.Update
body: <p>I have noticed, by using log4net, that when calling ISession.Update, it updates all the changed objects.
  <br/>
  For example:</p>
  
  <pre><code>
  // Change 2 instances 
  user1.IsDeleted = true;
  user2.UserName = "Xyz";
  // Call session.Update to update the 2 users
  using (ITransaction transaction = session.BeginTransaction())
  {
      Session.Update(user1); // This updates both user1 & user2
      transaction.Commit();
  }
  using (ITransaction transaction = session.BeginTransaction())
  {
      Session.Update(user2); // Now there is no need for this
      transaction.Commit();
  }
  </code></pre>
  
  <p>Is this the default behavior of NHibernate or has something to do with my mapping file?
  <br/>
  Can I make NHibernate update one by one?</p>