全局错误.Asax以及如何存储数据库中的数据

我在全局得到了错误。Asax和如何从数据库存储数据，这是尝试自己

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Web;
 using System.Web.Mvc;
 using System.Web.Routing;

 namespace DemoApplication
 {
     public class MvcApplication : System.Web.HttpApplication
     {        
         protected void Application_Start()
         {
             AreaRegistration.RegisterAllAreas();
             RouteConfig.RegisterRoutes(RouteTable.Routes);
         }
        public void Application_BeginRequest(Object source, EventArgs e)
         {
             if (!Settings.initialized)
             {
                 new Settings().Init();
             }
         }
     }
     public partial class Settings
     {
         public static bool UseProducts { get; set; }
         public static int SiteID { get; set; }
         public static bool initialized;
         /// Constructor
         public Settings()
         {
             initialized = false;
         }
         /// Initializes the class
         public void Init()
         {
             if (!initialized)
                 RetrieveAllSettings();
             initialized = true;
         }
         /// Loads all the settings from the db
         private void RetrieveAllSettings()
         {
             DataContext db = new DataContext();
             var settingval = (from s in db.websiteSettings
                               select s).SingleOrDefault();
             if (settingval != null)
             {
                 UseProducts = settingval.UseProducts;
                 SiteID = settingval.SiteID;
             }
         }
     }
 }