Linq to Entity 学习笔记（一）：实体模型的理解

 

 

 

        该篇学习了实体模型相关知识：

（一）实体模型得组成：

（1）概念模型:用概念架构定义语言(CSDL)Conceptual schema definition language表示。
（2）存储模型：用存储架构定义语言(SSDL)Store schema definition language 表示

（3）映射信息：用映射规范语言 (MSL)

（二）以员工部门实体为列讲解。

（1）实体示例：截图

（2）对添加的*.edmx,右键打开方式，选择，可以看到如下截图：

（3）其三种模型得XML代码：

<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="2.0" xmlns:edmx="http://schemas.microsoft.com/ado/2008/10/edmx">
  <!-- EF Runtime content -->
  <edmx:Runtime>
    <!-- SSDL content -->
    <edmx:StorageModels>
      <Schema Namespace="MyDBModel.Store" Alias="Self" Provider="System.Data.SqlClient" ProviderManifestToken="2008" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" xmlns="http://schemas.microsoft.com/ado/2009/02/edm/ssdl">
        <EntityContainer Name="MyDBModelStoreContainer">
          <EntitySet Name="Department" EntityType="MyDBModel.Store.Department" store:Type="Tables" Schema="dbo"/>
          <EntitySet Name="Employee" EntityType="MyDBModel.Store.Employee" store:Type="Tables" Schema="dbo"/>
          <AssociationSet Name="FK_Employee_Department" Association="MyDBModel.Store.FK_Employee_Department">
            <End Role="Department" EntitySet="Department"/>
            <End Role="Employee" EntitySet="Employee"/>
          </AssociationSet>
        </EntityContainer>
        <EntityType Name="Department">
          <Key>
            <PropertyRef Name="DepartmentID"/>
          </Key>
          <Property Name="DepartmentID" Type="int" Nullable="false" StoreGeneratedPattern="Identity"/>
          <Property Name="DepartmentName" Type="nvarchar" Nullable="false" MaxLength="50"/>
        </EntityType>
        <EntityType Name="Employee">
          <Key>
            <PropertyRef Name="EmployeeID"/>
          </Key>
          <Property Name="EmployeeID" Type="int" Nullable="false" StoreGeneratedPattern="Identity"/>
          <Property Name="EmployeeName" Type="nvarchar" Nullable="false" MaxLength="50"/>
          <Property Name="DepartmentID" Type="int" Nullable="false"/>
        </EntityType>
        <Association Name="FK_Employee_Department">
          <End Role="Department" Type="MyDBModel.Store.Department" Multiplicity="1"/>
          <End Role="Employee" Type="MyDBModel.Store.Employee" Multiplicity="*"/>
          <ReferentialConstraint>
            <Principal Role="Department">
              <PropertyRef Name="DepartmentID"/>
            </Principal>
            <Dependent Role="Employee">
              <PropertyRef Name="DepartmentID"/>
            </Dependent>
          </ReferentialConstraint>
        </Association>
      </Schema>
    </edmx:StorageModels>
    <!-- CSDL content -->
    <edmx:ConceptualModels>
      <Schema Namespace="MyDBModel" Alias="Self" xmlns:annotation="http://schemas.microsoft.com/ado/2009/02/edm/annotation" xmlns="http://schemas.microsoft.com/ado/2008/09/edm">
        <EntityContainer Name="MyDBEntities" annotation:LazyLoadingEnabled="true">
          <EntitySet Name="Departments" EntityType="MyDBModel.Department"/>
          <EntitySet Name="Employees" EntityType="MyDBModel.Employee"/>
          <AssociationSet Name="FK_Employee_Department" Association="MyDBModel.FK_Employee_Department">
            <End Role="Department" EntitySet="Departments"/>
            <End Role="Employee" EntitySet="Employees"/>
          </AssociationSet>
        </EntityContainer>
        <EntityType Name="Department">
          <Key>
            <PropertyRef Name="DepartmentID"/>
          </Key>
          <Property Name="DepartmentID" Type="Int32" Nullable="false" annotation:StoreGeneratedPattern="Identity"/>
          <Property Name="DepartmentName" Type="String" Nullable="false" MaxLength="50" Unicode="true" FixedLength="false"/>
          <NavigationProperty Name="Employees" Relationship="MyDBModel.FK_Employee_Department" FromRole="Department" ToRole="Employee"/>
        </EntityType>
        <EntityType Name="Employee">
          <Key>
            <PropertyRef Name="EmployeeID"/>
          </Key>
          <Property Name="EmployeeID" Type="Int32" Nullable="false" annotation:StoreGeneratedPattern="Identity"/>
          <Property Name="EmployeeName" Type="String" Nullable="false" MaxLength="50" Unicode="true" FixedLength="false"/>
          <Property Name="DepartmentID" Type="Int32" Nullable="false"/>
          <NavigationProperty Name="Department" Relationship="MyDBModel.FK_Employee_Department" FromRole="Employee" ToRole="Department"/>
        </EntityType>
        <Association Name="FK_Employee_Department">
          <End Role="Department" Type="MyDBModel.Department" Multiplicity="1"/>
          <End Role="Employee" Type="MyDBModel.Employee" Multiplicity="*"/>
          <ReferentialConstraint>
            <Principal Role="Department">
              <PropertyRef Name="DepartmentID"/>
            </Principal>
            <Dependent Role="Employee">
              <PropertyRef Name="DepartmentID"/>
            </Dependent>
          </ReferentialConstraint>
        </Association>
      </Schema>
    </edmx:ConceptualModels>
    <!-- C-S mapping content -->
    <edmx:Mappings>
      <Mapping Space="C-S" xmlns="http://schemas.microsoft.com/ado/2008/09/mapping/cs">
        <EntityContainerMapping StorageEntityContainer="MyDBModelStoreContainer" CdmEntityContainer="MyDBEntities">
          <EntitySetMapping Name="Departments"><EntityTypeMapping TypeName="MyDBModel.Department"><MappingFragment StoreEntitySet="Department">
            <ScalarProperty Name="DepartmentID" ColumnName="DepartmentID"/>
            <ScalarProperty Name="DepartmentName" ColumnName="DepartmentName"/>
          </MappingFragment></EntityTypeMapping></EntitySetMapping>
          <EntitySetMapping Name="Employees"><EntityTypeMapping TypeName="MyDBModel.Employee"><MappingFragment StoreEntitySet="Employee">
            <ScalarProperty Name="EmployeeID" ColumnName="EmployeeID"/>
            <ScalarProperty Name="EmployeeName" ColumnName="EmployeeName"/>
            <ScalarProperty Name="DepartmentID" ColumnName="DepartmentID"/>
          </MappingFragment></EntityTypeMapping></EntitySetMapping>
        </EntityContainerMapping>
      </Mapping>
    </edmx:Mappings>
  </edmx:Runtime>
  <!-- EF Designer content (DO NOT EDIT MANUALLY BELOW HERE) -->
  <Designer xmlns="http://schemas.microsoft.com/ado/2008/10/edmx">
    <Connection>
      <DesignerInfoPropertySet>
        <DesignerProperty Name="MetadataArtifactProcessing" Value="EmbedInOutputAssembly"/>
      </DesignerInfoPropertySet>
    </Connection>
    <Options>
      <DesignerInfoPropertySet>
        <DesignerProperty Name="ValidateOnBuild" Value="true"/>
        <DesignerProperty Name="EnablePluralization" Value="False"/>
        <DesignerProperty Name="IncludeForeignKeysInModel" Value="True"/>
      </DesignerInfoPropertySet>
    </Options>
    <!-- Diagram content (shape and connector positions) -->
    <Diagrams>
      <Diagram Name="Model1">
        <EntityTypeShape EntityType="MyDBModel.Department" Width="1.5" PointX="0.75" PointY="1" Height="1.45359375" IsExpanded="true"/>
        <EntityTypeShape EntityType="MyDBModel.Employee" Width="1.5" PointX="3" PointY="0.875" Height="1.6222135416666674" IsExpanded="true"/>
        <AssociationConnector Association="MyDBModel.FK_Employee_Department" ManuallyRouted="false">
          <ConnectorPoint PointX="2.25" PointY="1.726796875"/>
          <ConnectorPoint PointX="3" PointY="1.726796875"/>
        </AssociationConnector>
      </Diagram>
    </Diagrams>
  </Designer>
</edmx:Edmx>

（三）*.edmx中的Designer.

（1）截图：

(2)MyDBEntities : ObjectContext。并且重写了数据库连接。