I've no idea what you say :)
What I try to say are followings:
1) Among of all class definitions, the User, Customer, Bid, BidDetails can be created, altered, deleted during the course of the application service.
2) The category is a pre-defined system level data. It is a read-only data for all users. It shoull not be created, changed, or deleted by any users under the normal circumstance.
I am curious about the existence of the findByExample, makePersistent, and makeTransient methods in the DAO class based on the above two points.
Hope I clarify myself this time.