title: Linq OrderBy breaks with navigation property being null
body: <p>Working with four tables.</p>
  
  <p>Users -> has basic user info including a userid and a departmentid (int)<br>
  Groups -> basic group info including a groupid<br>
  GroupsMembers -> table that has the relationship between a group and it's members, many to many relationship, so groupid and userid are the columns<br>
  Departments -> basic department info including deptid</p>
  
  <p>I have a fk from the departmentid in the users table to the deparmtnet id in the departments table.</p>
  
  <p>FK from groups groupid to groupsmembers groupid
  FK from users userid to groupsmembers userid</p>
  
  <p>This allows the groups in the edmx to have a users navigation property which will have all the members of the group.</p>
  
  <pre><code>var grp = grpSource.FirstOrDefault(g =&gt; g.GroupID == groupID)
  if (grp.GroupID &gt; 0)
  {
      var userQuery = from u in grp.Users
                      where !u.Deleted
                      select u;
      userQuery = userQuery.OrderBy(u =&gt; u.Department.Name);
  }
  </code></pre>
  
  <p>I am including Users.Department.</p>
  
  <p>The problem comes because users do not have to have a department, so the departmentid column is nullable.  If there are any users for which the departmentid is null,  the orderby breaks and says u.Department is null.  If no departmentids are null, it works great.  I need a way to sort based on Department.Name even if there are null departmentids.  Any suggestions?</p>