title: What is the best approach to update only changed properties in NHibernate when session detached?
body: <p>I am working on the project which uses NHibernate. 
  I don't keep session opened. When i need to get or save object, i open the session, do what i need and then close the session. So all the time i'm working with objects detached from session.</p>
  
  <p>For example, when i need to get object from the database, i open the session, then call session.Get() and close the session. Then i update some properties of detached object. When i need to save changes to the database i call method that opens session, calls session.Update(myObject) and closes the session.</p>
  
  <p>But when i do so, NHibernate generates sql that updates all the fields I have mapped, even though they have not changed. My suggestion is when objects is detached from session, NHibernate couldn't track the changes has been made.
  What approach do you use when you want to update only properties that has been changed for object detached from session? How do you track the changes for detached objects?</p>
  
  <p>Thanks</p>