如何处理继承表上的级联删除？

Question

使用继承表时，我遇到了ON DELETE CASCADE的问题。

我有以下表格（模型第一）

现在，如果我想删除Entity1中的条目。

using (var ctx = new MyEntities())
{
   var first = ctx.Entity1Set.First();
   ctx.DeleteObject(first);
   ctx.SaveChanges();
}

简单......但SaveChanges抛出以下异常。

  

DELETE语句与REFERENCE约束冲突   FK_EntityA_inherits_BaseEntity“。数据库中发生冲突   “MyDB”，表“dbo.BaseEntitySet_EntityA”，列“Id”。该声明   已被终止。

我该如何解决这个问题？

---

更新

我注意到VS2010和VS2012模型设计器如何输出SQL之间存在差异。

VS2010 ：

-- Creating foreign key on [Id] in table 'BaseEntitySet_EntityA'
ALTER TABLE [dbo].[BaseEntitySet_EntityA]
ADD CONSTRAINT [FK_EntityA_inherits_BaseEntity]
    FOREIGN KEY ([Id])
    REFERENCES [dbo].[BaseEntitySet]
        ([Id])
    ON DELETE NO ACTION ON UPDATE NO ACTION;
GO

-- Creating foreign key on [Id] in table 'BaseEntitySet_EntityB'
ALTER TABLE [dbo].[BaseEntitySet_EntityB]
ADD CONSTRAINT [FK_EntityB_inherits_BaseEntity]
    FOREIGN KEY ([Id])
    REFERENCES [dbo].[BaseEntitySet]
        ([Id])
    ON DELETE NO ACTION ON UPDATE NO ACTION;
GO

注意 ON DELETE NO ACTION

VS2012

-- Creating foreign key on [Id] in table 'BaseEntitySet_EntityA'
ALTER TABLE [BaseEntitySet_EntityA]
ADD CONSTRAINT [FK_EntityA_inherits_BaseEntity]
    FOREIGN KEY ([Id])
    REFERENCES [BaseEntitySet]
        ([Id])
    ON DELETE CASCADE ON UPDATE NO ACTION;
GO

-- Creating foreign key on [Id] in table 'BaseEntitySet_EntityB'
ALTER TABLE [BaseEntitySet_EntityB]
ADD CONSTRAINT [FK_EntityB_inherits_BaseEntity]
    FOREIGN KEY ([Id])
    REFERENCES [BaseEntitySet]
        ([Id])
    ON DELETE CASCADE ON UPDATE NO ACTION;
GO

注意 ON DELETE CASCADE

那是相当重要的......

Answer 1

Visual Studio 2010 ADO实体设计器中似乎存在一个错误，导致生成错误的SQL。

<强> VS2010：

-- Creating foreign key on [Id] in table 'BaseEntitySet_EntityA'
ALTER TABLE [dbo].[BaseEntitySet_EntityA]
ADD CONSTRAINT [FK_EntityA_inherits_BaseEntity]
    FOREIGN KEY ([Id])
    REFERENCES [dbo].[BaseEntitySet]
        ([Id])
    ON DELETE NO ACTION ON UPDATE NO ACTION;
GO

-- Creating foreign key on [Id] in table 'BaseEntitySet_EntityB'
ALTER TABLE [dbo].[BaseEntitySet_EntityB]
ADD CONSTRAINT [FK_EntityB_inherits_BaseEntity]
    FOREIGN KEY ([Id])
    REFERENCES [dbo].[BaseEntitySet]
        ([Id])
    ON DELETE NO ACTION ON UPDATE NO ACTION;
GO

注意 ON DELETE NO ACTION

<强> VS2012

-- Creating foreign key on [Id] in table 'BaseEntitySet_EntityA'
ALTER TABLE [BaseEntitySet_EntityA]
ADD CONSTRAINT [FK_EntityA_inherits_BaseEntity]
    FOREIGN KEY ([Id])
    REFERENCES [BaseEntitySet]
        ([Id])
    ON DELETE CASCADE ON UPDATE NO ACTION;
GO

-- Creating foreign key on [Id] in table 'BaseEntitySet_EntityB'
ALTER TABLE [BaseEntitySet_EntityB]
ADD CONSTRAINT [FK_EntityB_inherits_BaseEntity]
    FOREIGN KEY ([Id])
    REFERENCES [BaseEntitySet]
        ([Id])
    ON DELETE CASCADE ON UPDATE NO ACTION;
GO

注意 ON DELETE CASCADE

将这些更改应用到数据库后，我可以毫无问题地删除。