public partial class WebForm2 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            using (NorthwindEntities ctx = new NorthwindEntities())
            {
                var query = (from q in ctx.Employees
                             select q).FirstOrDefault();//首先獲取記錄
                query.FirstName = "FIRST";//更改記錄
                ctx.Entry(query).State = System.Data.EntityState.Detached;//把當前實體從上下文中detach掉，否則在Update方法中無法更新
                int result = Update(query);//呼叫更新方法
            }
        }
        private int Update(Employee entity)
        {
            string error = string.Empty;
            using (NorthwindEntities ctx = new NorthwindEntities())
            {
                try
                {
                    ctx.Entry(entity).State = System.Data.EntityState.Modified;//指定狀態為更新
                    return ctx.SaveChanges();//儲存
                }
                catch (DbEntityValidationException ex)
                {
                    foreach (var item in ex.EntityValidationErrors)
                    {
                        foreach (var item2 in item.ValidationErrors)
                        {
                            error = string.Format("{0}:{1}\r\n", item2.PropertyName, item2.ErrorMessage);
                        }
                    }
                }

            }
            return 1;
        }
    }