title: Entity's primary key field is set to 0 instead of null
body: <p>I have a Person entity type like so:</p>
  
  <pre><code>public partial class Person
  {    
      public int PersonID { get; set; }
      public byte Gender { get; set; }
      public string IDNumber { get; set; }
  }
  </code></pre>
  
  <p>When I create a new Person for the purpose of saving him to the db, the primary key, PersonID, is set to 0, instead of null.</p>
  
  <p>the code:</p>
  
  <pre><code>var theNewGuy = new MyEntities.Person();
  </code></pre>
  
  <p>right after this line, theNewGuy.PersonID = 0. The question is, how would I tell it to insert a new Person and assign it the next available primary key? Obviously, I don't want it to be 0, yet there is already a Person in the db with PersonID = 0;</p>
  
  <p>The save code:</p>
  
  <pre><code>Velo.People.Add(theNewGuy);
  Velo.SaveChanges();//throws error
  </code></pre>
  
  <p>Exception thrown: 
  <strong>Violation of PRIMARY KEY constraint 'PK_PERSON'. Cannot insert duplicate key in object 'dbo.Person'. The duplicate key value is (0).
  The statement has been terminated.</strong></p>