Hello... I have a collumn as unique=true.. in Exam class.... I found that because transactions are commited automaticaly so to force the commit i use em.commit()

However i would like to know how to check if it is unique.Running a query isnt a solution because it may be an instert after checking because of the concurency....

Which is the best way to check for uniqness?

List<Exam_Normal> exam_normals = exam.getExam_Normal();
    exam.setExam_Normal(null);

    try {
        em.persist(exam);
        em.flush();

        Long i = 0L;
        if (exam_normals != null) {
            for (Exam_Normal e_n : exam_normals) {
                i++;
                e_n.setItem(i);
                e_n.setId(exam);
                em.persist(e_n);
            }
        }
    } catch (Exception e) {
        System.out.print("sfalma--");
    }
}

d