title: EF's DatabaseGeneratedOption.Identity attribute doesn't work for the ulong type
body: <pre><code>[Table( "User" )]
  public class User
  {
      [Key]
      [DatabaseGeneratedAttribute( DatabaseGeneratedOption.Identity )]
      public ulong Id { get; set; }
      // other columns
  }
  </code></pre>
  
  <p>For this code I get the exception: </p>
  
  <blockquote>
    <p>System.Data.Entity.Edm.EdmEntityType: : EntityType 'User' has no key
    defined. Define the key for this EntityType.</p>
  </blockquote>
  
  <p>But changing the Id's type to int, everything works fine. </p>
  
  <pre><code>    //...
      [DatabaseGeneratedAttribute( DatabaseGeneratedOption.Identity )]
      public int Id { get; set; }
      //...
  </code></pre>
  
  <p>How to get the possibility for autocreating tables with an Id having a ulong type capacity ? (using ef's code first obviously)</p>