<EntityType Name="BlogPost">
   <Key>
      <PropertyRef Name="BlogPostID" />
   </Key>
   <Property Name="BlogPostID" Type="Int32" Nullable="false" />
   <Property Name="BlogEntry" Type="String" Nullable="false" MaxLength="Max" 
             Unicode="true" FixedLength="false" />
   <Property Name="BlogDate" Type="DateTime" Nullable="false" />
   <Property Name="BlogTitle" Type="String" Nullable="false" MaxLength="500" 
             Unicode="true" FixedLength="false" />
   <Property Name="BlogType" Type="Int32" Nullable="false" />
   <Property Name="CityVisited" Type="String" MaxLength="200"
             Unicode="true" FixedLength="false" />
   <Property Name="CountryVisited" Type="String" MaxLength="200" Unicode="true" 
             FixedLength="false" />
   <Property Name="DateVisited" Type="DateTime" />

   <NavigationProperty Name="Blog" Relationship=
                       "MyTravelPostModel.FK_BlogPosts_Blogs"
                       FromRole="BlogPosts" ToRole="Blogs" />
   <NavigationProperty Name="Pictures" Relationship=
                       "MyTravelPostModel.FK_Pictures_BlogPosts"
                       FromRole="BlogPosts" ToRole="Pictures" />
   <NavigationProperty Name="Comments" Relationship=
                       "MyTravelPostModel.BlogComments"
                       FromRole="BlogPosts" ToRole="Comments" />
</EntityType>

<ComplexType Name="Address">
    <Property Name="StreetAddress"
              Type="String" MaxLength="50" />
    <Property Name="Address2"
              Type="String" MaxLength="50" />
    <Property Name="City"
              Type="String" MaxLength="50" />
    <Property Name="Region"
              Type="String" MaxLength="50" />
    <Property Name="PostalCode"
              Type="String" MaxLength="50" />
    <Property Name="Country"
              Type="String" MaxLength="50" />
</ComplexType>

using (EntityConnection conn = new 
         EntityConnection("name=travelEntitiesGeneral"))
{
      conn.Open();
      EntityCommand cmd = conn.CreateCommand();
      cmd.CommandText = @"select c.BlogID 
         from travelEntitiesGeneral.Blogs as c 
         where c.BlogPosts.Count > 0";
      EntityDataReader reader = 
         cmd.ExecuteReader(CommandBehavior.SequentialAccess);
      while (reader.Read())
      {
         Console.WriteLine("BlogID = {0}", reader["BlogID"]);
      }
     conn.Close();
}

<EntitySetMapping Name="BlogPosts">
   <EntityTypeMapping TypeName="IsTypeOf(MyTravelPostModel.BlogPost)">
      <MappingFragment StoreEntitySet="BlogPosts">
         <ScalarProperty Name="BlogPostID" ColumnName="BlogPostID" />
         <ScalarProperty Name="BlogEntry" ColumnName="BlogEntry" />
         <ScalarProperty Name="BlogDate" ColumnName="BlogDate" />
         <ScalarProperty Name="BlogTitle" ColumnName="BlogTitle" />
         <ScalarProperty Name="BlogType" ColumnName="BlogType" />
         <ScalarProperty Name="CityVisited" ColumnName="CityVisited" />
         <ScalarProperty Name="CountryVisited" 
                         ColumnName="CountryVisited" />
         <ScalarProperty Name="DateVisited" ColumnName="DateVisited" />
      </MappingFragment>
   </EntityTypeMapping>
</EntitySetMapping>

using (ObjectContext context = new ObjectContext("name=travelEntities"))
    {
        //--- create a query for customers
        ObjectQuery<Person> personQuery = context.CreateQuery<Person>(
                     @"select value c from travelEntitiesGeneral.People 
                     as c where c.PersonID == 1");
        //--- by enumerating the query will be implicitly executed
        //--- against the store and you can now work with an
        //--- IEnumerable<Customer>
        foreach (Person c in personQuery)
        {
            //--- dereference anything you like from Customer
            Console.WriteLine(c.PersonID + ": " + c.Name);
            c.Name = "New Name";
        }
        try
        {
            context.SaveChanges();
        }
        catch (OptimisticConcurrencyException opt)
        {
            // catching this exception allows you to 
            // refresh travelEntities with either store/client wins
            // project the travelEntities into this failed travelEntities.
            var failedEntities = from e3 in opt.StateEntries
                                 select new { e3.Entity };

            // Note: in future you should be able to just pass 
            // the opt.StateEntities  
            // in to refresh.
            context.Refresh(RefreshMode.ClientWins, failedEntities.ToList());
            context.SaveChanges();
        }
    } 

using (MyTravelPostEntities travelEntities = new MyTravelPostEntities())
{
    // get the latest blog post, with the comments and the people
    // I'm querying for all the blog posts that are related to this blog.
    // I want to include the comments and the people who wrote the
    // comments.
    // I also want only the most recent posting.
    // Note: Since we use the EntityKey that is put on the EntityReference
    // we can either do a tracking query or use span.
    BlogPost post = (from bp in 
        travelEntities.BlogPosts
                              .Include("Comments.Person")
                              .Include("Blog")
                     where bp.Blog.BlogID == requestedBlog.BlogID
                     orderby bp.BlogDate descending
                     select bp).First();
    return post;
} 

static Uri baseService = new 
   Uri("http://localhost:17338/MyTravelPostService.svc");
MyPeople2Entities context = new MyPeople2Entities(baseService); 
    // get the comment that is being marked for deletion
    // and get the view state blog post.
BlogPost post = (BlogPost)ViewState["BlogPost"];

    // move the comment to the deleted comment selection. 
Comment deletedComment = post.Comments[e.RowIndex];

    // call the DeleteComment service
context.AttachTo("Comments", deletedComment);
context.DeleteObject(deletedComment);
DataServiceResponse r = context.SaveChanges();

    // reload page so that F5, refresh doesn't update all this data.
ReloadPage();

// the creation of the travel MyTravelPostEntities opens the connection 
// and sets up all the metadata information automatically for you.
using (MyTravelPostEntities travelEntities = new MyTravelPostEntities())
{
    // attach the comment and delete.
    travelEntities.Attach(deleteComment);

    // call delete on the object
    travelEntities.DeleteObject(deleteComment);

    try
    {
       travelEntities.SaveChanges();
    }
    catch (OptimisticConcurrencyException opt)
    {
      // catching this exception allows you to 
      // refresh travelEntities with either store/client wins
      // project the travelEntities into this failed travelEntities.
      var failedEntities = from e3 in opt.StateEntries
                           select new { e3.Entity };

     travelEntities.Refresh(RefreshMode.ClientWins, failedEntities.ToList());
     travelEntities.SaveChanges();
    }
}