Hi,
I'm new to the Java Persistence API and I'm trying to get the GlassFish JPA implementation working on a Tomcat installation. My persistence.xml file is looking pretty much like the example from
https://glassfish.dev.java.net/javaee5/persistence/entity-persistence-support.html.
I'm using an Oracle XE database where I have already some tables filled with data.
So my question now is: How can I read this data from the database?
I for example have a table called "CREDITCARDTYPES" which has a corresponding Entity called "CreditCardType" with only one field. I then tried the following:
EntityManager em = emf.createEntityManager();
String queryString = "SELECT c FROM CreditCardType c";
Query query = em.createQuery(queryString);
List result = query.getResultList();
System.out.println("Java Persistence query: " + queryString + " returns " + result.size() + " elements");
And there I always get a 0-size list back.
I then tried to insert a new CreditCardType like that:
EntityTransaction tx = em.getTransaction();
tx.begin();
CreditCardType c = new CreditCardType();
c.setCardType("ABC");
em.persist(c);
tx.commit();
And when I then execute the upper code again my list contains one element. I checked that the database table was updated and now contains that new entry which is alright (my table already had 2 other entries, so it now has 3). But what about the data that was already in the database table (these 2 other entries)? How do I get this? I thought that this should be available as well by calling query.getResultList().
Thank you very much for your help.
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