hi every body
i use nhibernate in my program and i use it to implement more than 14 classes
but i have this problem and i don't understand why nhibernate save objects to database
this is my code                 
Code:
ISession session = NHibernateHelper.GetCurrentSession();
                ITransaction tx = session.BeginTransaction();
                IQuery query = session.CreateQuery("select e from Employ as e");
                IList allEmploys = query.List();
                NHibernateHelper.CloseSession();
                    
                      //////get employs from database
                ((Library.Model_Classes.Employ)(allEmploys[0])).Fname = "www";
                ((Library.Model_Classes.Employ)(allEmploys[0])).Sname = "www";
                     ///////////update the first one
                session = NHibernateHelper.GetCurrentSession();
                tx = session.BeginTransaction();
                query = session.CreateQuery("select e from Employ as e");
                allEmploys = query.List();
                NHibernateHelper.CloseSession();
                /// now i get allEmploys[0].Fname="www" in database and in allEmploys List               /// i don't save any thing but the nhibernate save my changes to database
i don't want to save any thing with out use (save,update,..........) operation
thank you very much for your help