linq to sql 插入数据有关问题

linq to sql 插入数据问题
先看看代码

C# code

 private void button1_Click(object sender, EventArgs e)        {            UserRolesDataConText urdct = new UserRolesDataConText();            UserRoles u = new UserRoles() { Name = "菜鸟" };            urdct.UserRoles.InsertOnSubmit(u);            urdct.SubmitChanges();            MessageBox.Show("添加成功");        }

user类

C# code

 [Table(Name = "UserInfo")]    public class Users    {        private int userId;        [Column(IsPrimaryKey = true)]        public int UserId        {            get { return userId; }            set { userId = value; }        }        private string userName;        [Column]        public string UserName        {            get { return userName; }            set { userName = value; }        }        private string userPsw;        [Column]        public string UserPsw        {            get { return userPsw; }            set { userPsw = value; }        }        private int userRoleID;        [Column]        public int UserRoleID        {            get { return userRoleID; }            set { userRoleID = value; }        }        private EntityRef<UserRoles> userRole;        [Association(Storage = "userRole", ThisKey = "UserRoleID")]        public UserRoles UserRole        {            get { return this.userRole.Entity; }            set { this.userRole.Entity = value; }        }        private string depID;        [Column]        public string DepID        {            get { return depID; }            set { depID = value; }        }        private string speID;        [Column]        public string SpeID        {            get { return speID; }            set { speID = value; }        }        private string subID;        [Column]        public string SubID        {            get { return subID; }            set { subID = value; }        }        public Users() { }            }    /// <summary>    /// 强类型DataConText    /// </summary>    class UserDataContext : DataContext    {        public Table<Users> User;        public UserDataContext() : base("Data Source=.;Initial Catalog=ExamQuestionsBase;User ID=sa;pwd=123") { }    }

userRoles类

C# code

 [Table(Name = "UserRoles")]    public class UserRoles    {        private int userRoleID;        [Column(IsPrimaryKey = true)]        public int UserRoleID        {            get { return userRoleID; }            set { userRoleID = value; }        }        private EntitySet<Users> users;        [Association(Storage="users",OtherKey="UserRoleID")]        public EntitySet<Users> Users        {            get { return this.users; }            set { this.users.Assign(value); }        }        private string name;        [Column]        public string Name        {            get { return name; }            set { name = value; }        }        public UserRoles() { }        public UserRoles(string name)        {            this.Name = name;        }    }    /// <summary>    /// 强类型DataConText    /// </summary>    class UserRolesDataConText : DataContext    {        public Table<UserRoles> UserRoles;         public UserRolesDataConText() : base("Data Source=.;Initial Catalog=ExamQuestionsBase;User ID=sa;pwd=123") { }    }

问题是：执行到 urdct.UserRoles.InsertOnSubmit(u);这句的时候提示错误“未将对象引用设置到对象的实例”，求解决！！！

[解决办法]

class UserRolesDataConText : DataContext
{
public Table<UserRoles> UserRoles;
public UserRolesDataConText() : base("Data Source=.;Initial Catalog=ExamQuestionsBase;User ID=sa;pwd=123") { }
}


看你的这里，分析下你的代码：
 UserRolesDataConText urdct = new UserRolesDataConText(); //实例化UserRolesDataConText
UserRoles u = new UserRoles() { Name = "菜鸟" }; //实例化UserRoles ，并给初始值
urdct.UserRoles.InsertOnSubmit(u); //urdct.UserRoles == null 为什么？？因为你的第一步
urdct.SubmitChanges();
MessageBox.Show("添加成功");


修改下吧。。

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