In first part we discussed how natural keys are presented in database and domain model. I guess each who reads till this place have a question of to connect these representations. The answer is obvious by an object-relation mapper (ORM). I believe that most of my readers already use some ORM in their projects. Unfortunately, solutions right out-of-box using database information for creation natural keys in domain model or vice versa don't exist. Further we'll consider that offering us 2 most popular ORMs NHibernate 2.1 and Entity Framework 4.0.