我正在写一个 wpf 应用程序。我有一个本地数据库（sqlCE），其中有两个实体类对应于不同的表。第一个类是 Account，第二个类是 Movements。两个表之间存在一对多的关系：一个帐户可以有更多的动作。这是帐户类：
[Table]
public class Account
{
.....other private fields...
private Int16 iDA;
private EntitySet<Movement> movements;
...other properties with column attribute....
//primary key
[Column(IsPrimaryKey = true, Storage="iDA", IsDbGenerated = true, AutoSync = AutoSync.OnInsert, DbType = "smallint")]
public Int16 IDA
{
get { return iDA; }
private set { iDA = value; }
}
//association
[Association(Storage = "movements", OtherKey = "IDA")]
public EntitySet<Movement> Movements
{
get { return movements; }
set { this.movements.Assign(value); }
}
public Account()
{
this.movements = new EntitySet<Movement>();
}
}
这是运动课：
[Table]
public class Movement
{
...other fields...
private Int16 iDA;
private int iDM;
private EntityRef<Account> myAcc;
//primary key
[Column(IsPrimaryKey = true, IsDbGenerated = true, AutoSync = AutoSync.OnInsert, DbType = "int NOT NULL IDENTITY", Storage = "iDM")]
public int IDM
{
get { return iDM; }
set { iDM = value; }
}
//property links the two tables
[Column(DbType = "smallint", Storage="iDA", isPrimaryKey=true)]
public Int16 IDA
{
get { return iDA; }
set { iDA = value; }
}
//association
[Association(Storage = "myAcc", ThisKey = "IDA")]
public Account MyAccount
{
get { return this.myAcc.Entity; }
set { this.myAcc.Entity = value; }
}
......
public Movement()
{
this.myAcc = new EntityRef<Account>();
}
}
我定义 IDA 属性来链接这两个表。之后我编写 datacontext 类：
public class DataBase : DataContext
{
public Table<Account> AccountTable
{
get { return this.GetTable<Account>(); }
}
public Table<Movement> MovementTable
{
get { return this.GetTable<Movement>(); }
}
public DataBase(string connection) : base(connection) { }
}
在主类中我创建了数据库，但是当我尝试使用帐户对象填充它时，我得到了一个 sql 异常！我可以毫无问题地插入调用 InsertOnSubmit(Account a) 的数据，但是当我调用 SubmitChanges() 时，程序停止并且异常显示“列不能包含空值。[列名 = IDA，表名 = 账户]”。
任何人都可以帮助我吗？