Create database tables from eclipse link JPA entities

Question

I want to deploy my Java application to Heroku, I'm using eclipse link JPA.

To do that I need to create the tables via a Java, so far I've got the code below but how do I get the DDL to create a table. I'll be running the app on MySQL for development and Heroku is Postgres for production. Therefore, I'd like the create table statement to take this into account.

import javax.persistence.*;

public class SchemaCreator
{
  public static void main(String[] args)
  {
    EntityManagerFactory factory =
    Persistence.createEntityManagerFactory("bitcoin");
    EntityManager em = factory.createEntityManager();

    String ddl = /// <--- How do I get it ?

    em.createNativeQuery(ddl);
  }
}

Answer 1

OK, I figured it out.

If I add the following entried to my persistence.xml

<property name="eclipselink.ddl-generation" value="drop-and-create-tables"/>
<property name="eclipselink.ddl-generation.output-mode" value="database"/> 

Then when I first access an entity if it's not already in the dataabse a table will be created.