Linq to Sql学习之2

今天使用一对多的使用小记！

两个表UserInfo 和 Sort 一对多关系

 [Table(Name="userInfo")]
    public class UserInfo
    {  
        [Column(IsDbGenerated=true,IsPrimaryKey=true)]
        public  int id { set; get; }

        [Column]
        public string userName { set; get; }

        [Column]
       public   string pwd { set; get; }
     

        [Column]
      public  int age { set; get; }

    }

  [Table(Name="Score")]
  public  class Score
    { 
      [Column]
      int id { set; get; }

      [Column]
      public int chinese{set;get;}

      [Column]
      public int english { set; get; }

      [Column]
      public int userId { set; get; }

    }

    class Demo
    {
        static void Main(string[] args)
        {
            DataContext ds = new DataContext("server=.;database=demodb;user=sa;pwd=sa");
            Table<UserInfo>userInfos=ds.GetTable<UserInfo>();
            Table<Score>scores=ds.GetTable<Score>();

 //两张表内联           

var user = from u in userInfos join s in scores on u.id equals s.userId select new { UserName=u.userName,Pwd=u.pwd,Age=u.age};

            foreach(var userInfo in user)
            Console.WriteLine(string.Format("{0},{1},{2}",userInfo.UserName,userInfo.Pwd,userInfo.Age));

        }
    }

  //以上形式比较显示体现了两表连接 ，是否可以自动关联起来  答案那是肯定的，，，，

 在UserInfo中添加对多方的Score的引用

//userId 是在Score中引用UserInfo的一个外键   是集合  理论上可以理解成IList<Score>

 [Association(OtherKey="userId")]
        public EntitySet<Score> Scores { set; get; }

在Score中体现一的一方  也就是UserInfo

添加 

   private EntityRef<UserInfo> userInfo;

        ////userId是Score表中的外键
        [Association(Storage="userInfo",ThisKey="userId",IsForeignKey=true)]
        public UserInfo UserInfo
        {
            get { return userInfo.Entity; }
            set { userInfo.Entity = value; }
        }

测试：

            DataContext ds = new DataContext("server=.;database=demodb;user=sa;pwd=sa");
            Table<UserInfo>userInfos=ds.GetTable<UserInfo>();

            var  user = from u in userInfos  where u.id==1  select u;

            UserInfo userInfo = user.Single<UserInfo>();

            if (userInfo != null)
            {
            
                Console.WriteLine("用户：" + userInfo.userName);
                foreach (Score s in userInfo.Scores)
                {
                    Console.WriteLine(string.Format("语文成绩：{0}  英语成绩{1}", s.chinese, s.english));
                }
            }

  //查询用户的时候 其成绩也是已经加载到了该用户中了。

  DataContext ds = new DataContext("server=.;database=demodb;user=sa;pwd=sa");
 
            Table<Score> Scores = ds.GetTable<Score>();

  var score = from s in Scores where s.id == 1 select s;

            Score scoreTest = score.Single<Score>();

            Console.WriteLine(string.Format("用户：{0} 语文成绩：{1}",scoreTest.UserInfo.userName,scoreTest.chinese));

       查询成绩也会加载出该用户！