实体框架的缓存？

Question

我有一些DB的结构，它有2个名为Sections和Surgeons的表，它们之间没有相互关联。我创建了一个模型，它看起来像：

好。现在我在这两个表之间创建一个关系：

没关系。现在我尝试从数据库＆＃34;更新模型，没有任何反应。奇怪。尝试删除模型并重新创建。同样，科和外科医生之间没有任何关系。为什么会这样？实体框架缓存了吗？怎么解决？ 我使用Visual Studio 2013 + MVC 5 + Entity Framework 6.1.2 + MS SQL 2014

增加： 我肯定会添加这些表的脚本：

CREATE TABLE [dbo].[Sections](
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [SectionName] [nvarchar](250) NOT NULL,
 CONSTRAINT [PK_Sections] PRIMARY KEY CLUSTERED 
(
    [ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]


CREATE TABLE [dbo].[Surgeons](
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [FirstName] [nvarchar](150) NOT NULL,
    [LastName] [nvarchar](150) NOT NULL,
    [SectionID] [int] NOT NULL,
 CONSTRAINT [PK_Surgeons] PRIMARY KEY CLUSTERED 
(
    [ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

ALTER TABLE [dbo].[Surgeons]  WITH CHECK ADD  CONSTRAINT [FK_Surgeons_Sections] FOREIGN KEY([SectionID])
REFERENCES [dbo].[Sections] ([ID])
ON UPDATE CASCADE
ON DELETE CASCADE
GO

ALTER TABLE [dbo].[Surgeons] CHECK CONSTRAINT [FK_Surgeons_Sections]