static void Main(string[] args){// 创建一个网关接口,TestData是数据库名TestDataEntities td = new TestDataEntities();// 创建一个实体对象,Student是表映射过来的对象,将其赋值Student st1 = new Student();st1.StudentID = "s4";st1.StudentName = "test1";st1.Age = 20;// 将实体对象添加到网关接口，插入操作td.Student.AddObject(st1);// 网关保存并改变td.SaveChanges();Console.WriteLine("添加成功！");}

    class Program{// 创建一个网关接口,TestData是数据库名,静态方法只能调用静态类static TestDataEntities stuEntities = new TestDataEntities();static void Main(string[] args){// 创建一个实体对象,Student是表映射过来的对象,将其赋值Student st1 = new Student();st1.StudentID = "s4";st1.StudentName = "小明";st1.Age = 20;//InsertStu(st1);//DeleteStu("s4");//Student stu2 = FindStudentByID("s4");//stu2.StudentName = "小明";//UpdateStu(stu2);//Console.WriteLine(stu2.StudentName);}// 添加操作public static void InsertStu(Student stu){// 将实体对象添加到网关接口,插入操作stuEntities.Student.AddObject(stu);// 网关保存并改变stuEntities.SaveChanges();Console.WriteLine("添加成功！ID:"+stu.StudentID);}// 删除操作public static void DeleteStu(string ID){Student stu = FindStudentByID(ID);stuEntities.Student.DeleteObject(stu);stuEntities.SaveChanges();Console.WriteLine("删除成功！ID:" + stu.StudentID);}// 更新操作public static void UpdateStu(Student stu){// 其中 var 为 IQueryable<Student>类型,继承IEnumerable<Student>// 继承IEnumerable的类都能实现 foreachvar student = from s in stuEntities.Studentwhere s.StudentID == stu.StudentIDselect s;// 得到student集合里面的单一实体var oldStu = student.SingleOrDefault();// 修改对应的属性值oldStu.StudentName = stu.StudentName;oldStu.Age = stu.Age;// 保存修改stuEntities.SaveChanges();Console.WriteLine("更新成功！ID:" + stu.StudentID);}// 更新数据 新方法public bool UpdateEntity(MvcHotel.Model.Customer entity){bool result = false;// 添加对象到上下文he.Attach(entity);// 改变新加入对象的状态,设置为 已修改he.ObjectStateManager.ChangeObjectState(entity, System.Data.EntityState.Modified);if (he.SaveChanges() > 0){result = true;}return result;}// 查询操作public static Student FindStudentByID(string ID){// 方式1： Linq to EF// 根据ID查询Student,并得到集合中的单一实体var stu = (from s in stuEntities.Studentwhere s.StudentID == IDselect s).SingleOrDefault();// 方式2： Entity SQLstring sql = "select Value c from TestDataEntities.Student as c ";ObjectQuery<Student> query = stuEntities.CreateQuery<Student>(sql);ObjectResult<Student> results = query.Execute(MergeOption.NoTracking);//return stu;return query.SingleOrDefault();}}