public ActionResult Index()
        {
            using (var dbc = new DBModel.SchoolEntities())
            {
                var objectContext = (dbc as IObjectContextAdapter).ObjectContext;
            };
            return View();
        }

public class Blog
    {
        public int BlogID { get; set; }
        public string BlogName { set; get; }
        public virtual List<Post> Posts { get; set; }
    }

public class Post
    {
        public int PostID { get; set; }
        public string Title { get; set; }
        public string Content { get; set; }
        public int BlogID { get; set; }
        public virtual Blog Bolg { get; set; }
    }

public class BlogingContext : DbContext
    {
        public DbSet<Blog> Blogs { get; set; }
        public DbSet<Post> Posts { get; set; }
    }

using (var dbc = new CodeFirst.BlogingContext())
            {
                dbc.Blogs.Add(new CodeFirst.Blog { BlogID = 1, BlogName = "qiaowen" });
                dbc.SaveChanges();
                //保存在哪里了呢 dbcontext首先找这台计算机上有没有sql dbcontext express instance 的实例,如果找不到sqlexpress的实例那么就会去找localdb的实例
            }

protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Blog>().Property(b => b.BlogUrl).HasColumnName("urladdress");
        }

using (var dbc = new CodeFirstFromDB())
            {
                dbc.Blogs.Add(new Blogs { BlogName = "ExistBlogName" });
                dbc.SaveChanges();
            }