How to access the JDBC connection?
Sometimes when using JPA it may be required to have lower level access to your database through JDBC. If you are using a JEE DataSource, you can just access the same DataSource that JPA uses, if it is a JTA DataSource it will be in the same transaction context as JPA. If you are not using a DataSource, or want the same connection in the same transaction as JPA, you can obtain the JDBC Connection from the EntityManager.
