title: How to update nested objects in NPoco
body: <p>I can't find an example of updating a nested object in a many-to-one situation. It's pretty clear how the mapping works on a Fetch; and I'm not speaking of updating a collection of nested objects, just one. So given the following example:</p>
  
  <pre><code>public class Student
  {
      public int StudentId { get; set; }
      public string Name { get; set; }
      [ResultColumn]
      public School CurrentSchool { get; set; }
  }
  
  public class School
  {
      public int SchoolId { get; set; }
      public string Name { get; set; }
  }
  </code></pre>
  
  <p>In the database, the Student table carries a CurrentSchool column that is the ID of a record in the School table. </p>
  
  <p>I'm not updating the School object itself, rather mapping the student to a different one. This is fine on a Query, but if I change the CurrentSchool object on the Student and save with db.Update(studentObject), the foreign key doesn't update.</p>