EntityFramework [2]: 增,删,改

static void Main(string[] args) { int result=0; using (Entities en=new Entities()) { Msg pm=new Msg(); pm.DMID=2; pm.enabled=false; pm.msgName="name"; pm.msgRecipients="2"; pm.priority=2; pm.replyTo="replyto"; pm.rssEnabled=false; pm.rssExpirationDate=DateTime.Now; pm.adminNotes="adminnotes"; pm.body="body"; pm.dateCreated=DateTime.Now; pm.dateDistributed=DateTime.Now; pm.dateModified=DateTime.Now; pm.deleted=false; pm.enabled=true; pm.IsToAllClinics=2; pm.sender=""; pm.status=2; pm.subject="sub"; //1.添加 en.AddToMsg(pm); result=en.SaveChanges(); Console.WriteLine(result > 0 ? "添加成功!" : "添加失败!"); //2.删除 //注:此处即为取满足条件的第一个元素. 2.不能用First, First会造成取不到时发生异常, 而FirstOrDefault则会赋null Msg delObj = en.Msg.FirstOrDefault(p => p.msgId == 114); //注:此处要判断是否为空 if(delObj!=null) en.DeleteObject(delObj); result=en.SaveChanges(); Console.WriteLine(result > 0 ? "删除成功!" : "删除失败!"); //3.更新 Msg upObj = en.Msg.FirstOrDefault(p => p.msgId == 110); upObj.msgName = "zzz"; upObj.enabled = false; result = en.SaveChanges(); Console.WriteLine(result > 0 ? "更新成功!" : "更新失败!"); //4.查询 } Console.ReadLine(); }