我是EF4的开端人,我无法理解 file子档案中的内容。
任何人都可以向我解释协会的好处。 我认为,协会要素代表了各表之间的关系,因此,我应该使用协会。
感谢
我是EF4的开端人,我无法理解 file子档案中的内容。
任何人都可以向我解释协会的好处。 我认为,协会要素代表了各表之间的关系,因此,我应该使用协会。
感谢
协会是一个协会的集装箱。
当我们有合同和地址类型时,让我们从简单的个案开始。 其关系可描述为:
<Association Name="FK_Address_Contact">
<End Role="Contact" Type="SampleModel.Contact" Multiplicity="1">
<OnDelete Action="Cascade" />
</End>
<End Role="Address" Type="SampleModel.Address" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Contact">
<PropertyRef Name="ContactID" />
</Principal>
<Dependent Role="Address">
<PropertyRef Name="ContactID" />
</Dependent>
</ReferentialConstraint>
</Association>
你可以在这里看到,接触者可以有许多地址。 我们在此指出,这两种说法之间都有提及。 但是,如果在合同类型中,我们实际上能够有两个或两个以上地址,那么我们如何能够描述一个案例。 例如,工作压力和家庭压力。 在协会内,我们只能描述两种类型相互参照的事实,但在协会内部,我们还可以描述一种类型可以使用两种对其他类型同等的提法。
对于这种情况,我们可以界定下一个xml:
<EntityContainer Name="ContactsContainer" >
<EntitySet Name="WorkContacts" EntityType="SampleModel.Contact" />
<EntitySet Name="HomeContacts" EntityType="SampleModel.Contact" />
<EntitySet Name="WorkAddresses" EntityType="SampleModel.Address" />
<EntitySet Name="HomeAddresses" EntityType="SampleModel.Address" />
<AssociationSet Name="ToWorkAddress" Association="SampleModel.FK_Address_Contact">
<End Role="Contact" EntitySet="WorkContacts" />
<End Role="Address" EntitySet="WorkAddresses" />
</AssociationSet>
<AssociationSet Name="ToHomeAddress" Association="SampleModel.FK_Address_Contact">
<End Role="Contact" EntitySet="HomeContacts" />
<End Role="Address" EntitySet="HomeAddresses" />
</AssociationSet>
</EntityContainer>
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