private static ISession _session ;
  public IList<int> list()
        {
using  (_session = factory.Session)
            {
                IQuery querys = _session.CreateQuery(“select  id from news”);
                return querys.List<int>();

            }
}

 
 private static ISessionFactory _factory;
       static object obj = new object();
       public ISession Session
       {
           get
           {
               if (_factory == null)
               {
                   lock (obj)
                   {
                       if (_factory == null)
                       {
                           Configuration cf = new Configuration().Configure();
                           _factory = cf.BuildSessionFactory();
                       }
                   }
               }
               return _factory.OpenSession();
           }
       }