Look the MainTest Class, note the delete.
I Use query, no session.delete(...) and this form i have problens

It´s bug in core hibernate or what?

How can i use Query to delete without have problems as this?





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Hibernate version:
Hibernate core 3.3.1GA

Mapping documents:
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.entity">
<class name="Car">
<id type="long" column="idCar" name="idCar" access="property" unsaved-value="undefined">
<generator class="native">
<param name="sequence">seqPkIdCar</param>
</generator>
</id>

<property name="description" length="15"/>

<bag name="travelList" inverse="true" access="property" >
<key column="fkCar" />
<one-to-many class="Travel" />
</bag>

</class>
</hibernate-mapping>


<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.entity">
<class name="Travel">
<id type="long" column="idTravel" name="idTravel" access="property" unsaved-value="undefined">
<generator class="native">
<param name="sequence">seqPkIdTravel</param>
</generator>
</id>

<property name="description" length="15" />

<many-to-one name="car" column="fkCar" class="Car" />
</class>
</hibernate-mapping>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.username">wssiv</property>
<property name="hibernate.connection.password">18012001</property>
<property name="hibernate.connection.url">jdbc:postgresql://192.168.10.15/sim3gt</property>
<property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
<property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>

<!-- Mapping -->
<mapping resource="com/entity/Car.hbm.xml" />
<mapping resource="com/entity/Travel.hbm.xml" />
</session-factory>
</hibernate-configuration>



Full stack trace of any exception that occurs:
Exception in thread "main" org.hibernate.exception.ConstraintViolationException: could not execute update query
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:94)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.hql.ast.exec.BasicExecutor.execute(BasicExecutor.java:107)
at org.hibernate.hql.ast.QueryTranslatorImpl.executeUpdate(QueryTranslatorImpl.java:419)
at org.hibernate.engine.query.HQLQueryPlan.performExecuteUpdate(HQLQueryPlan.java:283)
at org.hibernate.impl.SessionImpl.executeUpdate(SessionImpl.java:1168)
at org.hibernate.impl.QueryImpl.executeUpdate(QueryImpl.java:117)
at com.MainTest.main(MainTest.java:54)
Caused by: org.postgresql.util.PSQLException: ERROR: update or delete on table "car" violates foreign key constraint "fk95cb6b3a78a8fea5" on table "travel"
Detalhe: Key (idcar)=(1) is still referenced from table "travel".
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:1548)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1316)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:191)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:452)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:351)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:305)
at org.hibernate.hql.ast.exec.BasicExecutor.execute(BasicExecutor.java:98)
... 5 more






public class MainTest {

/**
* @param args
*/
public static void main(String[] args) {
Configuration cfg = new Configuration().configure();
SessionFactory sessionFactory = cfg.buildSessionFactory();
Session session = sessionFactory.openSession();
session.beginTransaction();

// Find Car
Criteria critCar = session.createCriteria(Car.class);
critCar.add(Restrictions.eq("idCar", new Long(1)));
Car car = (Car) critCar.uniqueResult();

// unlink travel
Criteria critTravel = session.createCriteria(Travel.class);
Criteria crit = critTravel.createAlias("car", "car");
crit.add(Restrictions.eq("car", car));
List lst = crit.list();
for (Iterator iterator = lst.iterator(); iterator.hasNext();) {
Travel travel = (Travel) iterator.next();
travel.setCar(null);
session.saveOrUpdate(travel);
}

// Here ... Probleman
// delete car
StringBuilder sb = new StringBuilder("DELETE FROM ");
sb.append(car.getClass().getCanonicalName());
sb.append(" AS DEL WHERE DEL.id");
sb.append(car.getClass().getSimpleName());
sb.append(" = ");
sb.append(car.getIdCar());

Query query = session.createQuery(sb.toString());
int row = query.executeUpdate();

session.getTransaction().commit();
}
}

You do not have to call this. Hibernate will automatically track changes you make to objects loaded in the session. However, everything is just kept internally in memory until you tell Hibernate to flush the changes to the database. That is why your DELETE query is failing. Hibernate has not yet pushed the changes from travel.setCar(null); to the database. To make this happen you should call session.flush() just before you execute the DELETE query.