Session session = HibernateSessionFactory.currentSession();
Transaction tx = session.beginTransaction();

EmployePO employePO = (EmployePO)session.load(EmployePO.class,"e001");
employePO.setDepartmentNo("d002"); //The original DepartmentNo is "d001"
employePO.setEmployeName("Jason Lian");

tx.commit();

EmployePO employePO2 = (EmployePO)session.load(EmployePO.class,"e001");

//This result is right "d002".
System.out.println("-------------------DepartmentNo from employePO:"+employePO2.getDepartmentNo());

//my question is just here,why the result is "d001",and how can I get the right result?
System.out.println("-------------------DepartmentNo from departmentPO:"+employePO2.getDepartmentPO().getDepartmentNo());

Any suggestion will be appreciated.

was it a typo that in the first sys out you asked for employePO2.getDepartmentNo() , but in the second you asked for employePO2.getDepartmentPO().getDepartmentNo() ?

if your employee actually has a property departmentNo as well as an object DepartmentPO which has a departmentNo then that's your problem, because you'll have updated the employee column departmentNo, but not the associated record DepartmentPO.

I have mapped like this in EmployePO.hbm.xml

Can anyone help?

Can you show the code from relevent POJOs?

Strikes me that you have mapped BOTH a 'property' and 'many-to-one'... shouldn't it be only a 'many-to-one'?

/C