休眠：无法删除实体

Question

I am trying to delete Entities in a JPA/Hibernate configuration. The database is an embedded HSQL file.

This is code doing the delete:

        EntityManager em = PersistenceUtility.getInstance().createEntityManager();
        EntityTransaction t = em.getTransaction();
        t.begin();

        List<ServiceTicket> tickets = em.createQuery("from ServiceTicket").getResultList();

        for (ServiceTicket ticket : tickets) {
            Report report = ticket.getReport();
            em.merge(report);
            em.merge(ticket);
            em.remove(report);
            em.remove(ticket);
        }

        em.flush();
        t.commit();

The ServiceTicket references the entitiy Report . This is why I had to remove Report first.

I do not get an error in this context. But the changes are not written to the database.

Here is the configuration of the persistence unit:

<persistence-unit name="local_hsql" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<class>Report</class>
<class>ServiceTicket</class>
<properties>
  <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
  <property name="hibernate.connection.url" value="jdbc:hsqldb:file:etc/database/db1"/>
  <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
  <property name="hibernate.cache.provider_class" value="org.hibernate.cache.NoCacheProvider"/>
  <property name="hibernate.show_sql" value="false"/>
  <property name="hibernate.connection.SetBigStringTryClob" value="true"/>
  <property name="hibernate.hbm2ddl.auto" value="update"/>
</properties>

What am I doing wrong?

Thanks in advance and regards from Germany

Marco

Answer 1

you can use

@OneToOne(cascade = CascadeType.REMOVE)

It will delete Report when you remove ServiceTicket.

Second: If you want to delete all ServiceTickets where something equals x you can use HQL:

Query query = session.createQuery("delete ServiceTicket where something = :x");
query.setParameter("x", "myvalue");
int result = query.executeUpdate();