EF 增删改查

StudentEntities entities = new StudentEntities();       //初始化对象
            Register register = new Register();
            #region 增加
            //register.UserName = "张三";
            //register.Pwd = "123";
            //register.Sex = "男";
            //register.Phone = "123456";
            //register.Age = "20";
            //register.Address = "河南郑州";
            //entities.Register.Add(register);            //添加一个集合使用Add
            //entities.SaveChanges();                      //保存
            #endregion

            #region 删除
            //Register r = entities.Register.Where(i=>i.Id==39).SingleOrDefault();       //在这里需要注意的是Lambda表达式的i属性Register，它是一个集合，所以需要它.出来他的id项
            //entities.Register.Remove(r);          //删除使用的是Remove
            //entities.SaveChanges();
            #endregion

            #region 修改
            //Register rr = entities.Register.Where(i => i.Id == 40).SingleOrDefault();     //修改时间记得先查询要修改的条件
            //rr.UserName = "zhangsan";        //在这里需要注意的是接受的对象
            //rr.Pwd = "456";
            //rr.Sex = "女";
            //rr.Phone = "123456789";
            //rr.Age = "20";
            //rr.Address = "北京";
            //entities.SaveChanges();             //保存
            #endregion

            #region 查询
            //Register rrr = entities.Register.Where(i => i.Id == 41).SingleOrDefault();
            //Console.WriteLine("{0},{1},{2}",rrr.Id,rrr.UserName,rrr.Pwd);

            //Register rrr = entities.Register.SelectMany(i=>i.Id==40&&i.Id==41).SelectMany();