Can you elaborate on your question. Not sure what you are asking.
JDO injects SQL into your Java classes. I don't think there are any changes to the database itself. If you are asking about data being stored. Transactions are handled by JDO, and all the CRUD and database constraints are followed.
The database takes care of data integrity when using relational jdo implementations. Some implementations will create the tables and contraints for you if you wish. To enrich the data integrity you create additional constraints using DDL scripts or define new ones in the jdo metadata definition.
Joined: Dec 06, 2003
JDO injects SQL into your Java classes.
JDO does not inject SQL into java classes. Your java classes are datastore agnostic and can be simultaneously used for xml store, relational store, file stores and others.
On the other hand, EJB CMP injects SQL code into classes at deployment time.