Well, the problem is when I try to save the "prueba", hibernate JPA tells me
javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: could not insert: [model.Inscripcion]
Caused by: java.sql.SQLException: Field 'id_prueba' doesn't have a default value
About the schema, a "prueba" has many "inscripcion", an "inscripcion" has ONLY one "prueba". So I don't agree that "prueba" should have a foreign key pointing "inscripcion", but "inscripcion" a foreign key pointing to "prueba". Don't you think so?