Difference in save/ update/ saveorUpdate

Hibernate has set of methods for saving and updating the values in the database. The methods which you are using are for updating its states and ultimately updated in database after the unit of work is completed. That happens when flush method is called.

·         Save: Save method stores an object into the database. That means it insert an entry if the identifier doesn’t exist, else it will throw error. If the primary key already present in the table, it cannot be inserted.

·         Update: Update method in hibernate is used for updating the object using identifier. If the identifier is missing or doesn’t exist, it will throw exception.

·         saveOrUpdate: This method calls save() or update() based on the operation. If the identifier exists, it will call update method else the save method will be called. saveOrUpdate() method does the following:

§  If the object is already persistent in the current session, it do nothing

§  If another object associated with the session has the same identifier, throw an exception to the caller

§  If the object has no identifier property, save() the object

§  If the object’s identifier has the value assigned to a newly instantiated object, save() the object