我有一个人表，一个雇员表和一个承包商表。所有员工都是人，所有承包商都是人，每个人都是员工或承包商。像这样:
我将如何使用Model First来完成这个概念？遗产？
最佳答案
该表结构+继承== TPT。在设计器中，它将如下所示:
...以及用于实体和到这些表的映射的原始EDMX:
<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="2.0" xmlns:edmx="http://schemas.microsoft.com/ado/2008/10/edmx" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" xmlns:ssdl="http://schemas.microsoft.com/ado/2009/02/edm/ssdl" xmlns:edm="http://schemas.microsoft.com/ado/2008/09/edm" xmlns:annotation="http://schemas.microsoft.com/ado/2009/02/edm/annotation" xmlns:map="http://schemas.microsoft.com/ado/2008/09/mapping/cs" xmlns:codegen="http://schemas.microsoft.com/ado/2006/04/codegeneration" xmlns:huagati="http://www.huagati.com/edmxtools/annotations">
<!--Updated by Huagati EDMX Tools version 2.16.4007.30259 on 2010-12-23 09:13:27-->
<!-- EF Runtime content -->
<edmx:Runtime>
<!-- SSDL content -->
<edmx:StorageModels>
<Schema xmlns="http://schemas.microsoft.com/ado/2009/02/edm/ssdl" Namespace="Model1.Store" Alias="Self" Provider="System.Data.SqlClient" ProviderManifestToken="2008">
<EntityContainer Name="Model1TargetContainer">
<EntitySet Name="Person" store:Type="Tables" Schema="dbo" Table="Person" store:Name="Person" EntityType="Model1.Store.Person" />
<EntitySet Name="Employee" store:Type="Tables" Schema="dbo" Table="Employee" store:Name="Employee" EntityType="Model1.Store.Employee" />
<AssociationSet Name="FK_Employee_Person" Association="Model1.Store.FK_Employee_Person">
<End Role="Person" EntitySet="Person" />
<End Role="Employee" EntitySet="Employee" />
</AssociationSet>
<EntitySet Name="Contractor" store:Type="Tables" Schema="dbo" Table="Contractor" store:Name="Contractor" EntityType="Model1.Store.Contractor" />
<AssociationSet Name="FK_Contractor_Person" Association="Model1.Store.FK_Contractor_Person">
<End Role="Person" EntitySet="Person" />
<End Role="Contractor" EntitySet="Contractor" />
</AssociationSet>
</EntityContainer>
<EntityType Name="Person">
<Documentation />
<Key>
<PropertyRef Name="PersonId" />
</Key>
<Property Name="PersonId" Type="bigint" Nullable="false" StoreGeneratedPattern="Identity" />
<Property Name="Name" Type="nvarchar" Nullable="true" MaxLength="50" />
</EntityType>
<EntityType Name="Employee">
<Documentation />
<Key>
<PropertyRef Name="EmployeeId" />
</Key>
<Property Name="EmployeeId" Type="bigint" Nullable="false" />
<Property Name="EmployeeNumber" Type="nvarchar" Nullable="true" MaxLength="50" />
</EntityType>
<Association Name="FK_Employee_Person">
<End Multiplicity="1" Role="Person" Type="Model1.Store.Person" />
<End Multiplicity="0..1" Role="Employee" Type="Model1.Store.Employee" />
<ReferentialConstraint>
<Principal Role="Person">
<PropertyRef Name="PersonId" />
</Principal>
<Dependent Role="Employee">
<PropertyRef Name="EmployeeId" />
</Dependent>
</ReferentialConstraint>
</Association>
<EntityType Name="Contractor">
<Documentation />
<Key>
<PropertyRef Name="ContractorId" />
</Key>
<Property Name="ContractorId" Type="bigint" Nullable="false" />
<Property Name="ContractorNumber" Type="nvarchar" Nullable="true" MaxLength="50" />
</EntityType>
<Association Name="FK_Contractor_Person">
<End Multiplicity="1" Role="Person" Type="Model1.Store.Person" />
<End Multiplicity="0..1" Role="Contractor" Type="Model1.Store.Contractor" />
<ReferentialConstraint>
<Principal Role="Person">
<PropertyRef Name="PersonId" />
</Principal>
<Dependent Role="Contractor">
<PropertyRef Name="ContractorId" />
</Dependent>
</ReferentialConstraint>
</Association>
</Schema>
</edmx:StorageModels>
<!-- CSDL content -->
<edmx:ConceptualModels>
<Schema xmlns="http://schemas.microsoft.com/ado/2008/09/edm" xmlns:cg="http://schemas.microsoft.com/ado/2006/04/codegeneration" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" Namespace="Model1" Alias="Self" xmlns:annotation="http://schemas.microsoft.com/ado/2009/02/edm/annotation">
<EntityContainer Name="Model1Container" annotation:LazyLoadingEnabled="true">
<EntitySet Name="Person" EntityType="Model1.Person" huagati:InheritanceStrategy="TPT" />
</EntityContainer>
<EntityType Name="Person">
<Key>
<PropertyRef Name="PersonId" />
</Key>
<Property Type="Int64" Name="PersonId" Nullable="false" annotation:StoreGeneratedPattern="Identity" />
<Property Type="String" Name="Name" Unicode="true" MaxLength="50" Nullable="true" />
</EntityType>
<EntityType Name="Employee" BaseType="Model1.Person">
<Property Type="String" Name="EmployeeNumber" Unicode="true" MaxLength="50" Nullable="true" />
</EntityType>
<EntityType Name="Contractor" BaseType="Model1.Person">
<Property Type="String" Name="ContractorNumber" Nullable="true" Unicode="true" MaxLength="50" />
</EntityType>
</Schema>
</edmx:ConceptualModels>
<!-- C-S mapping content -->
<edmx:Mappings>
<Mapping xmlns="http://schemas.microsoft.com/ado/2008/09/mapping/cs" Space="C-S">
<Alias Key="Model" Value="Model1" />
<Alias Key="Target" Value="Model1.Store" />
<EntityContainerMapping CdmEntityContainer="Model1Container" StorageEntityContainer="Model1TargetContainer">
<EntitySetMapping Name="Person">
<EntityTypeMapping TypeName="IsTypeOf(Model1.Person)">
<MappingFragment StoreEntitySet="Person">
<ScalarProperty Name="PersonId" ColumnName="PersonId" />
<ScalarProperty Name="Name" ColumnName="Name" />
</MappingFragment>
</EntityTypeMapping>
<EntityTypeMapping TypeName="IsTypeOf(Model1.Employee)">
<MappingFragment StoreEntitySet="Employee">
<ScalarProperty Name="PersonId" ColumnName="EmployeeId" />
<ScalarProperty Name="EmployeeNumber" ColumnName="EmployeeNumber" />
</MappingFragment>
</EntityTypeMapping>
<EntityTypeMapping TypeName="IsTypeOf(Model1.Contractor)">
<MappingFragment StoreEntitySet="Contractor">
<ScalarProperty Name="PersonId" ColumnName="ContractorId" />
<ScalarProperty Name="ContractorNumber" ColumnName="ContractorNumber" />
</MappingFragment>
</EntityTypeMapping>
</EntitySetMapping>
</EntityContainerMapping>
</Mapping>
</edmx:Mappings>
</edmx:Runtime>
<!-- EF Designer content (DO NOT EDIT MANUALLY BELOW HERE) -->
<edmx:Designer xmlns="http://schemas.microsoft.com/ado/2008/10/edmx">
<edmx:Connection>
<DesignerInfoPropertySet>
<DesignerProperty Name="MetadataArtifactProcessing" Value="EmbedInOutputAssembly" />
</DesignerInfoPropertySet>
</edmx:Connection>
<edmx:Options>
<DesignerInfoPropertySet>
<DesignerProperty Name="ValidateOnBuild" Value="true" />
<DesignerProperty Name="EnablePluralization" Value="True" />
</DesignerInfoPropertySet>
</edmx:Options>
<!-- Diagram content (shape and connector positions) -->
<edmx:Diagrams>
<Diagram Name="Model1">
<EntityTypeShape EntityType="Model1.Person" Width="1.5" PointX="5.125" PointY="2.125" Height="1.4033821614583331" />
<EntityTypeShape EntityType="Model1.Employee" Width="1.5" PointX="3.875" PointY="4" Height="1.2110807291666665" />
<InheritanceConnector EntityType="Model1.Employee">
<ConnectorPoint PointX="5.875" PointY="3.5283821614583331" />
<ConnectorPoint PointX="5.875" PointY="3.76" />
<ConnectorPoint PointX="4.625" PointY="3.76" />
<ConnectorPoint PointX="4.625" PointY="4" />
</InheritanceConnector>
<EntityTypeShape EntityType="Model1.Contractor" Width="2" PointX="5.875" PointY="4" Height="1.2110807291666665" />
<InheritanceConnector EntityType="Model1.Contractor" ManuallyRouted="false">
<ConnectorPoint PointX="5.875" PointY="3.5283821614583331" />
<ConnectorPoint PointX="5.875" PointY="3.76" />
<ConnectorPoint PointX="6.875" PointY="3.76" />
<ConnectorPoint PointX="6.875" PointY="4" />
</InheritanceConnector>
</Diagram>
</edmx:Diagrams>
</edmx:Designer>
</edmx:Edmx>
有关不同继承类型及其与物理数据库表的关系的详细说明，请参见:
http://huagati.blogspot.com/2010/10/mixing-inheritance-strategies-in-entity.html
...和...
http://blogs.msdn.com/b/adonet/archive/2010/10/25/inheritance-mapping-a-walkthrough-guide-for-beginners.aspx
关于.net - Entity Framework : Model First,继承吗？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/4514973/