Fluent nHibernate SchemaUpdate 不起作用

我首先使用Fluent nHibernate代码，我有Nullable列，然后更改为.Not.Nullable（）但我的列仍然可为空

这是我的配置

 public override void Load()
        {
            Bind<ISessionFactory>().ToMethod(x =>
             {
                 var factory = Fluently.Configure()
                     .Database(MsSqlConfiguration.MsSql2008.ConnectionString
                         (c => c.FromConnectionStringWithKey("DefaultConnection")))
                     .Mappings(m => m.FluentMappings.AddFromAssemblyOf<Users>()
                         .Conventions.Add(PrimaryKey.Name.Is(p => "Id"), ForeignKey.EndsWith("Id"))
                         .Conventions.Setup(c => c.Add(AutoImport.Never())))
                     .ExposeConfiguration(cfg => new SchemaUpdate(cfg).Execute(true, true));
                 return factory.BuildSessionFactory();
             }).InSingletonScope();
        }