This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
You got the set the key value for the newly created object. For example:
Then Hibernate will be able to identify that this object is already existing object and it just has to update the object. Else if there's no key or the key doesn't exist in DB, merge() will save it as a new object.