//显示加载

Console.WriteLine("=========查询集合===========");

using (var db = new Entities())

{

    var query = from v in db.Classes

                where v.ClassName == "机电10501"

                select v;

    var cls = query.Single();

    db.Entry(cls).Collection(v => v.Student).Load();//加载集合使用Collection方法

    Console.WriteLine("==========="+cls.ClassName);

    foreach (var stu in cls.Student)

    {

        Console.WriteLine(stu.StudentName);

    }

    //IsLoaded方法判断数据是否已经加载

    Console.WriteLine(db.Entry(cls).Collection(v => v.Student).IsLoaded);

}

//显示加载

Console.WriteLine("=========查询单个实体===========");

using (var db = new Entities())

{

    var student = db.Student.First();

    db.Entry(student).Reference(v => v.Classes).Load();//加载单个实体使用Reference方法

    Console.WriteLine(student.StudentName);

    Console.WriteLine(student.Classes.ClassName);

}

//按需查询

using (var db = new Entities())

{

    var query = from v in db.Student

                select new

                {

                    id=v.StudentID,

                    name=v.StudentName

                };

    foreach (var st in query)

    {

        ObjectDumper.Write(st);

    }

}