交换成员，确定对象的证书是不可能的。尝试使用新证书添加新对象

Question

你好！当我尝试使用帮助“linq to sql”更新我的表时，我得到一个异常，其中包含一条消息，上面写着这样的消息

1. 无法交换成员，确定对象的证书。尝试使用新证书添加新对象，然后删除现有对象。

2. 在DB中构建我的表是[Field1（int，PK），Field2（varchar（15），PK），Field3（varchar（32），PK），Field4（int，PK）]，那里没有任何约束和触发器。

3. 在MSSQL中，我可以进行任何操作，例如＆＃34;更新＆＃34;，＆＃34;插入＆＃34;和＆＃34;删除＆＃34;，但在我的应用程序中，我只能插入和删除我的记录

4. 我的实体类，根据DB

中的表格

[DataContract]
[Table(Name = "dbo.MyTable")]
public class MyTable: DataContext
{
    private int _Field1;

    private string _Field2;

    private string _Field3;

    private int _Field4;

    private EntityRef<MyTable1> _MyTable1;

    private EntityRef<MyTable2> _MyTable2;

    public event PropertyChangingEventHandler PropertyChanging;

    public event PropertyChangedEventHandler PropertyChanged;

    private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);

    protected virtual void SendPropertyChanging()
    {
        if ((this.PropertyChanging != null))
        {
            this.PropertyChanging(this, emptyChangingEventArgs);
        }
    }

    protected virtual void SendPropertyChanged(String propertyName)
    {
        if ((this.PropertyChanged != null))
        {
            this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    private void Initialize()
    {
        this._MyTable1 = new EntityRef<MyTable1>();
        this._MyTable2 = new EntityRef<MyTable2>();
    }

    public MyTable()
    {
        Initialize();
    }

    [Association(IsForeignKey = true, Name = "MyTable_MyTable1", OtherKey = "Field4", Storage = "_MyTable1", ThisKey = "Field4")]
    public MyTable1 MyTable1
    {
        get { return this._MyTable1.Entity; }
        set
        {
            MyTable1 entity = this._MyTable1.Entity;
            if (entity == value && this._MyTable1.HasLoadedOrAssignedValue)
                return;
            this.SendPropertyChanging();
            if (entity != null)
            {
                this._MyTable1.Entity = (MyTable1)null;
            }
            this._MyTable1.Entity = value;
            if (value != null)
            {
                this.Field4 = value.Field4;
            }
            else
            {
                this.Field4 = 0;
            }

            this.SendPropertyChanged("MyTable1");
        }
    }

    [Association(IsForeignKey = true, Name = "MyTable_MyTable2", OtherKey = "Field1", Storage = "_MyTable2", ThisKey = "Field1")]
    public MyTable2 MyTable2
    {
        get
        {
            return this._MyTable2.Entity;
        }
        set
        {
            MyTable2 entity = this._MyTable2.Entity;
            if (entity == value && this._MyTable2.HasLoadedOrAssignedValue)
                return;
            this.SendPropertyChanging();
            if (entity != null)
            {
                this._MyTable2.Entity = (MyTable2)null;
            }
            this._MyTable2.Entity = value;
            if (value != null)
            {
                this.Field1 = value.Field1;
            }
            else
            {
                this.Field1= 0;
            }

            this.SendPropertyChanged("MyTable2");
        }
    }

    [Column(DbType = "Int", Storage = "_Field1", IsPrimaryKey = true, CanBeNull = false)]
    [DataMember(Order = 1)]
    public int Field1
    {
        get
        {
            return this._Field1;
        }
        set
        {
            if ((this._Field1 != value))
            {
                this._Field1 = value;
            }
        }
    }

    [Column(DbType = "VARCHAR(15)", Storage = "_Field2", IsPrimaryKey = true, CanBeNull = false)]
    [DataMember(Order = 2)]
    public string Field2
    {
        get
        {
            return this._Field2;
        }
        set
        {
            if ((this._Field2 != value))
            {
                this._Field2 = value;
            }
        }
    }

    [Column(DbType = "VARCHAR(32)", Storage = "_Field3", IsPrimaryKey = true, CanBeNull = false)]
    [DataMember(Order = 3)]
    public string Field3
    {
        get
        {
            return this._Field3;
        }
        set
        {
            if ((this._Field3 != value))
            {
                this._Field3 = value;
            }
        }
    }

    [Column(DbType = "Int", Storage = "_Field4", IsPrimaryKey = true, CanBeNull = false)]
    [DataMember(Order = 4)]
    public int Field4
    {
        get
        {
            return this._Field4;
        }
        set
        {
            if ((this._Field4 != value))
            {
                this._Field4 = value;
            }
        }
    }
}

}