EF 自测例子

public ActionResult Test()
        {

            using (MvcShoppingContext db = new MvcShoppingContext())
            {
                var objectContext = ((IObjectContextAdapter)db).ObjectContext; //用来解决 未启用MSDTC错误
                try
                {                   
                    objectContext.Connection.Open();

                    //设置事务超时时间
                    //TransactionOptions transactionOption = new TransactionOptions();
                    //transactionOption.Timeout = new TimeSpan(0, 1, 0); //设置为1分钟

                    //事务处理,默认：隔离级别为可序列化 (Serializable)，事务的超时时间为 1 分钟
                    using (var scope = new TransactionScope())
                    {

                        //一、 单表增删改查

                        //1，增,--------------------------------------------------------
                        //Person p = new Person() { Name = "qjn", Age = 23, Gender = "female" };

                        //方法一
                        //db.Persons.Add(p);                                               
                        //db.SaveChanges();

                        //方法二
                        //db.Persons.Attach(p);
                        //db.Entry<Person>(p).State = System.Data.EntityState.Added;
                        //db.SaveChanges();

                        //2,改,只要实体的ID就可以了 -------------------------------------------

                        //方法一、修改所有字段,不设置的字段将会变为类型的默认字段，如string 将为null
                        //Person p = new Person() { Id = 1, Name = "QinHua", Age = 30 };
                        //db.Persons.Attach(p);
                        //db.Entry<Person>(p).State = System.Data.EntityState.Modified;
                        //db.SaveChanges();

                        //方法二、先查寻出来，再修改。注意：会发生未启用MSDTC错误，请注意觖决办法
                        //Person p = db.Persons.SingleOrDefault(m => m.Id == 1);
                        //p.Name = "Qin Hua";
                        //p.Gender = "Male";
                        //db.SaveChanges();

                        //方法三、修改部份字段，
                        //Person p = new Person() { Id = 1, Name = "Hua", Age = 25 };
                        //db.Persons.Attach(p);
                        //var setEntry = ((IObjectContextAdapter)db).ObjectContext.ObjectStateManager.GetObjectStateEntry(p);
                        //setEntry.SetModifiedProperty("Name");
                        //setEntry.SetModifiedProperty("Age");
                        //db.SaveChanges();

                        //3， 删--------------------------------------------------
                        //Person p = new Person() { Id = 2 };
                        //db.Persons.Attach(p);
                        //db.Persons.Remove(p);
                        //db.SaveChanges();

                        //4，并发处理，如果两IE同时执行此方法，将只有一个成功，另一个出错--------------
                        //Person p = db.Persons.Where(m => m.Id == 3).SingleOrDefault();
                        //p.Name = "N-" + DateTime.Now.ToString("mm:ss");
                        //System.Threading.Thread.Sleep(3000);
                        //db.SaveChanges();

                       //并发冲突时的解决办法(fail)：当发生冲突时，循环执行此过程。(当然还有其它方法),这个方法有问题，会引起事务中止
                        //int i = 0;
                        //int maxTimes = 3;
                        //bool isHaveError = false;
                        //do
                        //{
                        //    isHaveError = false;
                        //    try
                        //    {                             
                        //        Person p = db.Persons.Where(m => m.Id == 3).SingleOrDefault();
                        //        p.Name =   p.Name+" N-" + DateTime.Now.ToString("mm:ss");
                        //        System.Threading.Thread.Sleep(3000);
                        //        db.SaveChanges();
                        //    }
                        //    //catch (DbUpdateConcurrencyException ex)
                        //    //catch (System.Data.OptimisticConcurrencyException ex)
                        //    catch(DbUpdateException ex)
                        //    {                              
                        //        //当发生冲突时               
                        //        foreach (DbEntityEntry item in ex.Entries)
                        //        {                                   
                        //            objectContext.Refresh(
                        //           System.Data.Objects.RefreshMode.StoreWins, item.Entity);
                        //        }
                        //        //db.SaveChanges();               

                        //        isHaveError = true;
                        //        i++;
                        //    }
                        //} while (i < maxTimes && isHaveError);
                        //if (i >= maxTimes)
                        //{
                        //    throw new Exception("并发测试，抛出异常，数据更新过程中发生了并发错误");
                        //}

                        //并发冲突解决2(right)，由于是网站，所以用lock方式，（客户端软件可以考虑用数据库锁的方式)----------------------
                        //lock (lockObj)
                        //{
                        //    Person p = db.Persons.Where(m => m.Id == 3).SingleOrDefault();
                        //    p.Name = p.Name + " N-" + DateTime.Now.ToString("mm:ss");
                        //    System.Threading.Thread.Sleep(3000);
                        //    db.SaveChanges();
                        //}

                        //二、一对多、多对一关系处理

                        // 级联增 1,正向  [如果级联对象不存在，则会新增级联对象，否则不新增(如例2)]
                        //OrderH oh = new OrderH() { Name = "AA", OrderDs = new List<OrderD>() };
                        //OrderD od1 = new OrderD() { Price = 10 };
                        //OrderD od2 = new OrderD() { Price = 12 };
                        //oh.OrderDs.Add(od1);
                        //oh.OrderDs.Add(od2);
                        //db.OrderHs.Add(oh);
                        //db.SaveChanges();

                        // 级联增 2 ，加入到一个
                        //OrderH oh = db.OrderHs.Where(m => m.Id == 1).SingleOrDefault();
                        //OrderD od1 = new OrderD() { Price = 13, OrderH=oh };
                        //OrderD od2 = new OrderD() { Price = 14, OrderH = oh };
                        //db.OrderDs.Add(od1);
                        //db.OrderDs.Add(od2);
                        //db.SaveChanges();

                        // 级联增 2.2 ，加入到一个,[这样子会出错]
                        //OrderH oh = db.OrderHs.Where(m => m.Id == 5).SingleOrDefault();
                        //OrderD od1 = new OrderD() { Price = 13 };
                        //OrderD od2 = new OrderD() { Price = 14 };
                        //oh.OrderDs.Add(od1);
                        //oh.OrderDs.Add(od2);
                        //db.OrderHs.Add(oh);
                        //db.SaveChanges();

                        // 级联增 3，反向
                        //OrderH oh = new OrderH() { Name = "BB", OrderDs = new List<OrderD>() };
                        //OrderD od1 = new OrderD() { Price = 13, OrderH = oh };
                        //OrderD od2 = new OrderD() { Price = 14, OrderH = oh };
                        //db.OrderDs.Add(od1);
                        //db.OrderDs.Add(od2);
                        //db.SaveChanges();

                        // 级联增 4，各自保存各自的
                        //OrderH oh = new OrderH() { Name = "CC", OrderDs = new List<OrderD>() };
                        //OrderD od1 = new OrderD() { Price = 15, OrderH = oh };
                        //OrderD od2 = new OrderD() { Price = 16, OrderH = oh };
                        //db.OrderDs.Add(od1);
                        //db.OrderDs.Add(od2);
                        //db.OrderHs.Add(oh);
                        //db.SaveChanges();

                        // 级联增 5，各自保存各自的
                        //OrderH oh = new OrderH() { Name = "DD", OrderDs = new List<OrderD>() };

                        //OrderD od1 = new OrderD() { Price = 15, OrderH = oh };
                        //OrderD od2 = new OrderD() { Price = 16, OrderH = oh };

                        //oh.OrderDs.Add(od1);
                        //oh.OrderDs.Add(od2);

                        //db.OrderDs.Add(od1);
                        //db.OrderDs.Add(od2);
                        //db.OrderHs.Add(oh);
                        //db.SaveChanges();

                        //2,级联修改
                        //OrderH oh = db.OrderHs.Where(m => m.Id == 5).SingleOrDefault();
                        //OrderD od = null;
                        //foreach (var item in oh.OrderDs)
                        //{
                        //    od = item;
                        //    break;
                        //}                     
                        //oh.Name = "Modify";
                        //od.Price = 11;
                        //db.SaveChanges();

                        //3,级联删除

                        //只删除主键表是会出错的
                        //OrderH oh = db.OrderHs.Where(m => m.Id == 5).SingleOrDefault();
                        //db.OrderHs.Remove(oh);
                        //db.SaveChanges();

                        //只删除主键表是会出错的
                        //OrderH oh = new OrderH() { Id = 5 };
                        //db.OrderHs.Attach(oh);
                        //db.OrderHs.Remove(oh);
                        //db.SaveChanges();

                        //删除主表，并将子表的外键清空
                        //OrderH oh = db.OrderHs.Where(m => m.Id == 5).SingleOrDefault();
                        //OrderD od = null;
                        //foreach (var item in oh.OrderDs)
                        //{
                        //    od = item;
                        //    od.OrderH = null;
                        //}
                        //db.OrderHs.Remove(oh);
                        //db.SaveChanges();

                        //删除主表，并将子表的外键清空 2
                        //OrderH oh = db.OrderHs.Where(m => m.Id == 2).SingleOrDefault();
                        //oh.OrderDs.Clear();
                        //db.OrderHs.Remove(oh);
                        //db.SaveChanges();

                        //删除主表，并将子表删除,数据库里设置级联删除
                        OrderH oh = db.OrderHs.Where(m => m.Id == 1).SingleOrDefault();
                        db.OrderHs.Remove(oh);
                        db.SaveChanges();

                        //只将子表的外键清空 2
                        //OrderH oh = db.OrderHs.Where(m => m.Id == 1).SingleOrDefault();
                        //oh.OrderDs.Clear();
                        //db.SaveChanges();

                        //只将子表的外键清空 
                        //OrderH oh = db.OrderHs.Where(m => m.Id == 7).SingleOrDefault();
                        //OrderD od = null;
                        //foreach (var item in oh.OrderDs)
                        //{
                        //    od = item;
                        //    od.OrderH = null;
                        //}
                        //db.SaveChanges();

                       
                        //三、多对多的处理
                        //1,新增
                        //User u = new User() { Name = "qqh", NewRoles = new List<NewRole>() };
                        //NewRole nr = new NewRole() { Name = "r1" };
                        //u.NewRoles.Add(nr);
                        //db.Users.Add(u);
                        //db.SaveChanges();

                        //2，加入一笔新数据
                        //User u = new User() { Name = "hhyy", NewRoles = new List<NewRole>() };
                        //NewRole nr = db.NewRoles.Where(m => m.Id == 1).SingleOrDefault();
                        //u.NewRoles.Add(nr);
                        //db.Users.Add(u);
                        //db.SaveChanges();

                        //3,修改,将一个用户的角色删除
                        //User u = db.Users.Where(m => m.Id == 1).SingleOrDefault();
                        //u.Name = "tre";
                        //u.NewRoles.Clear();  //移除它的所有角色,中间表会清掉相关数据                
                        //db.SaveChanges();

                        //4,

                       
                        //throw new Exception("事务测试，抛出异常，事务将回滚");
                        scope.Complete();
                    }

                }
                catch (Exception ex)
                {
                    throw ex;
                }
                finally
                {
                    objectContext.Connection.Close();
                }
            }

            return View();

          
        }