difference between entitymanager merge and execute update

Question

What is the difference between

entitymanager.merge

and

query.executeUpdate

.

I have one entity order

@Entity

@Table(name="ORDERS",schema ="AMZ")

public class Orders {



    @Id

    @SequenceGenerator(name = "pk_sequence", sequenceName = "ORDERS_SEQ", schema = "AMZ", allocationSize = 1)

    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "pk_sequence")

    @Column(name = "ORDERS_ID")

    private long id;



    @Column(name = "STATUS")

    private Status status;

I have my DAO class

@Repository

@Transactional

public class InvoiceDAO {



    @PersistenceContext

    private EntityManager entityManager;



public void update(Order order){

updateInvoice();

mergeInvoice(Order order);

}



public void updateInvoice(){

entitymanager.createQuery("update Orders set status = 'ERROR' where id=12").executeUpdate();

}



public void mergeInvoice(Order order){

entitymanager.merge(order);

    }





}

In the above, merge happens before

executeUpdate();

even though there are several transactions in between execute update is the last transaction which occurs. WHY?

I tried

entityManager.flush();

but it didn't work.

Answer 1

I resolved this by calling the update and merge methods from service layer. I found that for the transaction to get commit I have to return out of my DAO.

public void update(Order order){
orderDao.updateInvoice();
orderDao.mergeInvoice(Order order);
}

difference between entitymanager merge and execute update

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