How can I update changed members in entity class object?

In hibernate,update object is set all table columns to sql. code for example:

//orm entity
class User {
    int id;
    string firstName;
    string lastName;

    }
Session sess = factory.openSession();
User user =sess.createQuery("FROM User WHERE first_name=:firstName").setParameter("firstName","balabala").uniqueResult!User();

user.lastName = "new balabala";//change last name

sess.update(user);

when exec update method ,hibernate generate sql like that

UPDATE user SET first_name =?, last_name =? WHERE id=?

but i just want to modify or update last_name column, maybe sql is

UPDATE user SET  last_name =? WHERE id=?

does hibernate has a method to update changed columns only？

how can i do that?

buggins / hibernated

How can I update changed members in entity class object? #50