HOW TO：使用每個階層的資料表繼承來定義模型 (Entity Framework)

發行項
08/21/2008

在實體資料模型 (EDM) 中，您可以使用許多方式來實作繼承 (Inheritance)。每個階層的資料表方法會在儲存體中使用某份資料表來維護繼承階層中所有型別的資料。本節含有在每個階層的資料表案例上實作之簡易繼承階層的結構描述和對應。

在 EDM 中，每個階層的資料表模型上繼承階層的概念結構描述會在衍生型別的宣告中包含 BaseType 屬性指派。即使儲存體模型僅使用一份資料表來管理這個案例的資料，系統仍然會個別宣告每個 EntityType。EntityContainer 的宣告僅包含基底類型 (Base Type) 的 EntitySet 宣告。

這個範例中的關聯是在基底類型上實作，因為關聯的定義會參考 EntitySet 宣告。衍生型別 (Derived Type) 在 EntityContainer 中沒有任何 EntitySet 宣告。

若要針對每個階層的資料表繼承階層架構來實作概念結構描述

建立類別庫 (Class Library) 專案並加入新的 ADO.NET 實體資料模型空白模型。
使用 XML 編輯器開啟 .edmx 檔案。
透過宣告 Person 實體基底型別，以及從此基底型別衍生 Student、Instructor 和 Administrator 實體，實作概念結構定義語言 (CSDL) 結構描述。
語法的使用方式如下所示。Student、Instructor 和 Administrator 型別都會繼承 Person 基底類型的屬性。Student 型別會加入 EnrollmentDate 屬性，而 Instructor 會加入 HireDate 屬性。
將 AdminDate 加入至 Administrator 實體，以便指定這位人員成為部門管理員的日期。
實作 Person 基底類型以及名為 People 之 EntitySet 以邏輯方式包含的衍生型別 Student 與 Instructor。

    <!-- CSDL content -->
    <edmx:ConceptualModels>
      <Schema xmlns="https://schemas.microsoft.com/ado/2006/04/edm" 
              Namespace="SchoolDataLib" Alias="Self">
        <EntityContainer Name="SchoolDataLibContainer">
          <EntitySet Name="Departments" 
                     EntityType="SchoolDataLib.Department" />
          <EntitySet Name="People" 
                     EntityType="SchoolDataLib.Person" />

          <AssociationSet Name="FK_Department_Administrator"
               Association="SchoolDataLib.FK_Department_Administrator">
            <End Role="Person" EntitySet="People" />
            <End Role="Department" EntitySet="Departments" />
          </AssociationSet>

        </EntityContainer>
        <EntityType Name="Department">
          <!--Base type table-per-type inheritance-->
          <Key>
            <PropertyRef Name="DepartmentID" />
          </Key>
          <Property Name="DepartmentID" Type="Int32" Nullable="false" />
          <Property Name="Name" Type="String" Nullable="false" />
          <Property Name="Budget" Type="Decimal" Nullable="false" />
          <Property Name="StartDate" Type="DateTime" Nullable="false" />
          <NavigationProperty Name="Administrator"
                 Relationship="SchoolDataLib.FK_Department_Administrator"
                 FromRole="Department" ToRole="Person" />
        </EntityType>

        <EntityType Name="DeptBusiness"
                    BaseType="SchoolDataLib.Department">
          <Property Name="LegalBudget" 
                    Type="Decimal" Nullable="false" />
          <Property Name="AccountingBudget" 
                    Type="Decimal" Nullable="false" />
        </EntityType>

        <EntityType Name="DeptEngineering" 
                    BaseType="SchoolDataLib.Department">
          <Property Name="FiberOpticsBudget" 
                    Type="Decimal" Nullable="false" />
          <Property Name="LabBudget" 
                    Type="Decimal" Nullable="false" />
        </EntityType>

        <EntityType Name="DeptMusic" 
                    BaseType="SchoolDataLib.Department">
          <Property Name="TheaterBudget" 
                    Type="Decimal" Nullable="false" />
          <Property Name="InstrumentBudget" 
                    Type="Decimal" Nullable="false" />
        </EntityType>

        <Association Name="FK_Department_Administrator">
          <End Role="Person" 
               Type="SchoolDataLib.Person" Multiplicity="0..1" />
          <End Role="Department" 
               Type="SchoolDataLib.Department" Multiplicity="*" />
        </Association>

        <EntityType Name="Person">
          <!--Base type table-per-hierarchy inheritance-->
          <Key>
            <PropertyRef Name="PersonID" />
          </Key>
          <Property Name="PersonID" Type="Int32" Nullable="false" />
          <Property Name="FirstName" Type="String" Nullable="false" />
          <Property Name="LastName" Type="String" Nullable="false" />
          <NavigationProperty Name="Department"
                 Relationship="SchoolDataLib.FK_Department_Administrator"
                 FromRole="Person" ToRole="Department" />
        </EntityType>

        <EntityType Name="Student" BaseType="SchoolDataLib.Person">
          <Property Name="EnrollmentDate" Type="DateTime" />
        </EntityType>

        <EntityType Name="Instructor" BaseType="SchoolDataLib.Person">
          <Property Name="HireDate" Type="DateTime" />
        </EntityType>

        <EntityType Name="Administrator" BaseType="SchoolDataLib.Person">
          <Property Name="AdminDate" Type="DateTime" />
        </EntityType>

      </Schema>
    </edmx:ConceptualModels>

若要針對每個階層的資料表繼承階層架構來實作儲存中繼資料

針對階層中的 Student、Instructor 和 Administrator 型別，在儲存體中實作一份資料表。
宣告三個衍生自 Person 基底型別的型別。只有 Person 資料表是包含所有衍生型別之資料所需的資料表。最後一個屬性 PersonCategory 是鑑別子資料行。它的值可用來指定其中一個型別的衍生執行個體 (Instance) 是 Student、Instructor 或 Administrator。

    <!-- SSDL content -->
    <edmx:StorageModels>
      <Schema xmlns="https://schemas.microsoft.com/ado/2006/04/edm/ssdl" 
              Namespace="SchoolDataLib.Target" 
              Alias="Self" Provider="System.Data.SqlClient" 
              ProviderManifestToken="2005">
        <EntityContainer Name="dbo">
          <EntitySet Name="Department" 
                     EntityType="SchoolDataLib.Target.Department" />
          <EntitySet Name="DeptBusiness" 
                     EntityType="SchoolDataLib.Target.DeptBusiness" />
          <EntitySet Name="DeptEngineering" 
                     EntityType="SchoolDataLib.Target.DeptEngineering" />
          <EntitySet Name="DeptMusic" 
                     EntityType="SchoolDataLib.Target.DeptMusic" />
          <EntitySet Name="Person" 
                     EntityType="SchoolDataLib.Target.Person" />

          <AssociationSet Name="FK_Department_Administrator"
              Association="SchoolDataLib.Target.FK_Department_Administrator">
            <End Role="Person" EntitySet="Person" />
            <End Role="Department" EntitySet="Department" />
          </AssociationSet>
        </EntityContainer>
        <EntityType Name="Department">
          <Key>
            <PropertyRef Name="DepartmentID" />
          </Key>
          <Property Name="DepartmentID" Type="int" Nullable="false" />
          <Property Name="Name" Type="nvarchar" 
                    Nullable="false" MaxLength="50" />
          <Property Name="Budget" Type="money" Nullable="false" />
          <Property Name="StartDate" Type="datetime" Nullable="false"/>
          <Property Name="Administrator" Type="int" />
        </EntityType>

        <EntityType Name="DeptBusiness">
          <Key>
            <PropertyRef Name="BusinessDeptID" />
          </Key>
          <Property Name="BusinessDeptID" 
                    Type="int" Nullable="false" />
          <Property Name="LegalBudget" 
                    Type="money" Nullable="false" />
          <Property Name="AccountingBudget" 
                    Type="money" Nullable="false" />
        </EntityType>

        <EntityType Name="DeptEngineering">
          <Key>
            <PropertyRef Name="EngineeringDeptID" />
          </Key>
          <Property Name="EngineeringDeptID" 
                    Type="int" Nullable="false" />
          <Property Name="FiberOpticsBudget" 
                    Type="money" Nullable="false" />
          <Property Name="LabBudget" 
                    Type="money" Nullable="false" />
        </EntityType>

        <EntityType Name="DeptMusic">
          <Key>
            <PropertyRef Name="DeptMusicID" />
          </Key>
          <Property Name="DeptMusicID" 
                    Type="int" Nullable="false" />
          <Property Name="TheaterBudget" 
                    Type="money" Nullable="false" />
          <Property Name="InstrumentBudget" 
                    Type="money" Nullable="false" />
        </EntityType>

        <EntityType Name="Person">
          <Key>
            <PropertyRef Name="PersonID" />
          </Key>
          <Property Name="PersonID"
                    Type="int" Nullable="false" />
          <Property Name="FirstName" 
                    Type="nvarchar" Nullable="false" MaxLength="50" />
          <Property Name="LastName" 
                    Type="nvarchar" Nullable="false" MaxLength="50" />
          <Property Name="HireDate" Type="datetime" />
          <Property Name="EnrollmentDate" Type="datetime" />
          <Property Name="AdminDate" Type="datetime" />
          <Property Name="PersonCategory" 
                    Type="smallint" Nullable="false" />
        </EntityType>

        <Association Name="FK_Department_Administrator">
          <End Role="Person" 
             Type="SchoolDataLib.Target.Person" Multiplicity="0..1"/>
          <End Role="Department" 
             Type="SchoolDataLib.Target.Department" Multiplicity="*"/>
          <ReferentialConstraint>
            <Principal Role="Person">
              <PropertyRef Name="PersonID" />
            </Principal>
            <Dependent Role="Department">
              <PropertyRef Name="Administrator" />
            </Dependent>
          </ReferentialConstraint>
        </Association>
      </Schema>
    </edmx:StorageModels>

若要使用 SQL Server Management Studio 來產生資料庫

在 SQL Server Management Studio 中，使用下列指令碼來產生這個範例以及 HOW TO：使用每個類型的資料表繼承來定義模型 (Entity Framework) 範例中所用的資料庫。
指向 [檔案] 功能表上的 [新增]，然後按一下 [Database Engine 查詢]，以便使用 SQL Server Management Studio 來建立 SchoolData 資料庫和結構描述。
在 [連接到 Database Engine] 對話方塊中，輸入 localhost 或另一個 SQL Server 執行個體的名稱，然後按一下 [連接]。
將下列 Transact-SQL 指令碼貼入查詢視窗中，然後按一下 [執行]。

USE [master]
GO

CREATE DATABASE [SchoolData] 
GO

USE [SchoolData]
GO

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[DeptBusiness]') AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[DeptBusiness](
    [BusinessDeptID] [int] NOT NULL,
    [LegalBudget] [money] NOT NULL,
    [AccountingBudget] [money] NOT NULL,
 CONSTRAINT [PK_DeptBusiness] PRIMARY KEY CLUSTERED 
(
    [BusinessDeptID] ASC
)WITH (PAD_INDEX  = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[DeptEngineering]') AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[DeptEngineering](
    [EngineeringDeptID] [int] NOT NULL,
    [FiberOpticsBudget] [money] NOT NULL,
    [LabBudget] [money] NOT NULL,
 CONSTRAINT [PK_DeptEngineering] PRIMARY KEY CLUSTERED 
(
    [EngineeringDeptID] ASC
)WITH (PAD_INDEX  = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[DeptMusic]') AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[DeptMusic](
    [DeptMusicID] [int] NOT NULL,
    [TheaterBudget] [money] NOT NULL,
    [InstrumentBudget] [money] NOT NULL,
 CONSTRAINT [PK_DeptMusic] PRIMARY KEY CLUSTERED 
(
    [DeptMusicID] ASC
)WITH (PAD_INDEX  = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Course]') AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[Course](
    [CourseID] [int] NOT NULL,
    [Title] [nvarchar](100) NOT NULL,
    [StartDate] [datetime] NOT NULL,
    [EndDate] [datetime] NOT NULL,
    [Credits] [int] NULL,
 CONSTRAINT [PK_Course] PRIMARY KEY CLUSTERED 
(
    [CourseID] ASC
)WITH (PAD_INDEX  = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Person]') AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[Person](
    [PersonID] [int] NOT NULL,
    [FirstName] [nvarchar](50) NOT NULL,
    [LastName] [nvarchar](50) NOT NULL,
    [HireDate] [datetime] NULL,
    [EnrollmentDate] [datetime] NULL,
    [PersonCategory] [smallint] NOT NULL,
    [AdminDate] [datetime] NULL,
 CONSTRAINT [PK_Person] PRIMARY KEY CLUSTERED 
(
    [PersonID] ASC
)WITH (PAD_INDEX  = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Enrollment]') AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[Enrollment](
    [EnrollmentID] [int] NOT NULL,
    [CourseID] [int] NOT NULL,
    [StudentID] [int] NOT NULL,
 CONSTRAINT [PK_Enrollment] PRIMARY KEY CLUSTERED 
(
    [EnrollmentID] ASC
)WITH (PAD_INDEX  = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[CourseInstructor]') AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[CourseInstructor](
    [CourseInstructorID] [int] NOT NULL,
    [CourseID] [int] NOT NULL,
    [InstructorID] [int] NOT NULL,
 CONSTRAINT [PK_CourseInstructor] PRIMARY KEY CLUSTERED 
(
    [CourseInstructorID] ASC
)WITH (PAD_INDEX  = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Department]') AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[Department](
    [DepartmentID] [int] NOT NULL,
    [Name] [nvarchar](50) NOT NULL,
    [Budget] [money] NOT NULL,
    [StartDate] [datetime] NOT NULL,
    [Administrator] [int] NULL,
 CONSTRAINT [PK_Department] PRIMARY KEY CLUSTERED 
(
    [DepartmentID] ASC
)WITH (PAD_INDEX  = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
END
GO
IF NOT EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id = OBJECT_ID(N'[dbo].[FK_Enrollment_Course]') AND parent_object_id = OBJECT_ID(N'[dbo].[Enrollment]'))
ALTER TABLE [dbo].[Enrollment]  WITH CHECK ADD  CONSTRAINT [FK_Enrollment_Course] FOREIGN KEY([CourseID])
REFERENCES [dbo].[Course] ([CourseID])
GO
ALTER TABLE [dbo].[Enrollment] CHECK CONSTRAINT [FK_Enrollment_Course]
GO
IF NOT EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id = OBJECT_ID(N'[dbo].[FK_Enrollment_Student]') AND parent_object_id = OBJECT_ID(N'[dbo].[Enrollment]'))
ALTER TABLE [dbo].[Enrollment]  WITH CHECK ADD  CONSTRAINT [FK_Enrollment_Student] FOREIGN KEY([StudentID])
REFERENCES [dbo].[Person] ([PersonID])
GO
ALTER TABLE [dbo].[Enrollment] CHECK CONSTRAINT [FK_Enrollment_Student]
GO
IF NOT EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id = OBJECT_ID(N'[dbo].[FK_CourseInstructor_Course]') AND parent_object_id = OBJECT_ID(N'[dbo].[CourseInstructor]'))
ALTER TABLE [dbo].[CourseInstructor]  WITH CHECK ADD  CONSTRAINT [FK_CourseInstructor_Course] FOREIGN KEY([CourseID])
REFERENCES [dbo].[Course] ([CourseID])
GO
ALTER TABLE [dbo].[CourseInstructor] CHECK CONSTRAINT [FK_CourseInstructor_Course]
GO
IF NOT EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id = OBJECT_ID(N'[dbo].[FK_CourseInstructor_Instructor]') AND parent_object_id = OBJECT_ID(N'[dbo].[CourseInstructor]'))
ALTER TABLE [dbo].[CourseInstructor]  WITH CHECK ADD  CONSTRAINT [FK_CourseInstructor_Instructor] FOREIGN KEY([InstructorID])
REFERENCES [dbo].[Person] ([PersonID])
GO
ALTER TABLE [dbo].[CourseInstructor] CHECK CONSTRAINT [FK_CourseInstructor_Instructor]
GO
IF NOT EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id = OBJECT_ID(N'[dbo].[FK_Department_Administrator]') AND parent_object_id = OBJECT_ID(N'[dbo].[Department]'))
ALTER TABLE [dbo].[Department]  WITH CHECK ADD  CONSTRAINT [FK_Department_Administrator] FOREIGN KEY([Administrator])
REFERENCES [dbo].[Person] ([PersonID])
GO
ALTER TABLE [dbo].[Department] CHECK CONSTRAINT [FK_Department_Administrator]

若要針對每個階層的資料表繼承階層架構來實作對應規格

將每個階層的資料表概念結構描述的實體對應至儲存結構描述中的實體。這個每個階層的資料表範例中所定義之三個型別的資料會包含在單一資料表中。此對應結構描述是使用對應規格語言 (MSL) 所撰寫。
在這個每個階層的資料表繼承的範例中，使用鑑別子資料行來指定階層中的型別。此結構描述中的 Condition 行包含 Column 和 Value 屬性。Value 為 0 的 PersonCategoryColumn 會指定基底型別 Person。Value 為 1 會指定 Student 型別、Value 為 2 會指定 Instructor 型別，而 Value 為 3 則指定 Administrator 型別。
在名為 People 的單一 EntitySetMapping 底下，對應階層中的三個 EntityTypeMapping 區段。完整的對應規格如下所示。

    <!-- C-S mapping content -->
    <edmx:Mappings>
      <Mapping xmlns="urn:schemas-microsoft-com:windows:storage:mapping:CS"
               Space="C-S">
        <Alias Key="Model" Value="SchoolDataLib" />
        <Alias Key="Target" Value="SchoolDataLib.Target" />
        <EntityContainerMapping CdmEntityContainer="SchoolDataLibContainer" 
                  StorageEntityContainer="dbo">
          
          <!-- Mapping for table-per-type inheritance-->
          <EntitySetMapping Name="Departments">
            <EntityTypeMapping 
                     TypeName="IsTypeOf(SchoolDataLib.Department)">
              <MappingFragment StoreEntitySet="Department">
                <ScalarProperty 
                     Name="DepartmentID" ColumnName="DepartmentID" />
                <ScalarProperty Name="Name" ColumnName="Name" />
                <ScalarProperty Name="Budget" ColumnName="Budget" />
                <ScalarProperty 
                     Name="StartDate" ColumnName="StartDate" />
              </MappingFragment>
            </EntityTypeMapping>

            <EntityTypeMapping TypeName="SchoolDataLib.DeptBusiness">
              <MappingFragment StoreEntitySet="DeptBusiness">
                <ScalarProperty Name="DepartmentID" 
                                ColumnName="BusinessDeptID" />
                <ScalarProperty Name="AccountingBudget" 
                                ColumnName="AccountingBudget" />
                <ScalarProperty Name="LegalBudget" 
                                ColumnName="LegalBudget" />
              </MappingFragment>
            </EntityTypeMapping>

            <EntityTypeMapping TypeName="SchoolDataLib.DeptEngineering">
              <MappingFragment StoreEntitySet="DeptEngineering">
                <ScalarProperty Name="DepartmentID" 
                                ColumnName="EngineeringDeptID" />
                <ScalarProperty Name="FiberOpticsBudget" 
                                ColumnName="FiberOpticsBudget" />
                <ScalarProperty Name="LabBudget" 
                                ColumnName="LabBudget" />
              </MappingFragment>
            </EntityTypeMapping>

            <EntityTypeMapping TypeName="SchoolDataLib.DeptMusic">
              <MappingFragment StoreEntitySet="DeptMusic">
                <ScalarProperty Name="DepartmentID" 
                                ColumnName="DeptMusicID" />
                <ScalarProperty Name="TheaterBudget" 
                                ColumnName="TheaterBudget" />
                <ScalarProperty Name="InstrumentBudget" 
                                ColumnName="InstrumentBudget" />
              </MappingFragment>
            </EntityTypeMapping>
          </EntitySetMapping>

          <!--Mapping for table-per-hierarchy inheritance-->
          <EntitySetMapping Name="People">
            <EntityTypeMapping TypeName="SchoolDataLib.Person">
              <MappingFragment StoreEntitySet="Person">
                <ScalarProperty Name="PersonID" ColumnName="PersonID"/>
                <ScalarProperty Name="FirstName" ColumnName="FirstName"/>
                <ScalarProperty Name="LastName" ColumnName="LastName"/>
                <Condition ColumnName="PersonCategory" Value="0" />
              </MappingFragment>
            </EntityTypeMapping>

            <EntityTypeMapping TypeName="SchoolDataLib.Student">
              <MappingFragment StoreEntitySet="Person">
                <ScalarProperty Name="PersonID" ColumnName="PersonID" />
                <ScalarProperty Name="FirstName" ColumnName="FirstName" />
                <ScalarProperty Name="LastName" ColumnName="LastName" />
                <ScalarProperty 
                  Name="EnrollmentDate" ColumnName="EnrollmentDate" />
                <Condition ColumnName="PersonCategory" Value="1" />
              </MappingFragment>
            </EntityTypeMapping>

            <EntityTypeMapping TypeName="SchoolDataLib.Instructor">
              <MappingFragment StoreEntitySet="Person">
                <ScalarProperty Name="PersonID" ColumnName="PersonID" />
                <ScalarProperty Name="FirstName" ColumnName="FirstName" />
                <ScalarProperty Name="LastName" ColumnName="LastName" />
                <ScalarProperty Name="HireDate" ColumnName="HireDate" />
                <Condition ColumnName="PersonCategory" Value="2" />
              </MappingFragment>
            </EntityTypeMapping>

            <EntityTypeMapping TypeName="SchoolDataLib.Administrator">
              <MappingFragment StoreEntitySet="Person">
                <ScalarProperty Name="PersonID" ColumnName="PersonID" />
                <ScalarProperty Name="FirstName" ColumnName="FirstName" />
                <ScalarProperty Name="LastName" ColumnName="LastName" />
                <ScalarProperty Name="AdminDate" ColumnName="AdminDate" />
                <Condition ColumnName="PersonCategory" Value="3" />
              </MappingFragment>
            </EntityTypeMapping>

          </EntitySetMapping>


          <AssociationSetMapping Name="FK_Department_Administrator"
                    TypeName="SchoolDataLib.FK_Department_Administrator"
                    StoreEntitySet="Department">
            <EndProperty Name="Person">
              <ScalarProperty Name="PersonID" ColumnName="Administrator" />
            </EndProperty>
            <EndProperty Name="Department">
              <ScalarProperty Name="DepartmentID" ColumnName="DepartmentID" />
            </EndProperty>
            <Condition ColumnName="Administrator" IsNull="false" />
          </AssociationSetMapping>
        </EntityContainerMapping>
      </Mapping>
    </edmx:Mappings>

另請參閱

工作

HOW TO：使用每個階層的資料表繼承來建立和執行物件查詢 (Entity Framework)
HOW TO：加入及修改具有每個階層的資料表繼承的物件 (Entity Framework)
HOW TO：使用每個階層的資料表繼承來建立和執行物件查詢 (Entity Framework)

概念

繼承 (EDM)

共用方式為