Question

I have two tables: Customers and Commands, it’s a @OneToMany relation from Client to Commands, one client have many Commands.
the table commands contain : idCommand, date, nameCommande, idCustomer.
the table customers contain: idCustomer, nameClient, email.
All the JPA and EJB are set up and I can easily get a list of Commands or Clients using an HQL query in a managed bean and list them in a JSP using this code.

 public List<Commande> selectAllCommandes() {
    List<Commande> commandes = em.createQuery("select c from Commande c").getResultList();
      return commandes;
}
 public List<Customer> selectAllCustomers() {
    List<Customer> customers = em.createQuery("select cu from Customer cu").getResultList();
    return customers;
}

How do I join the two tables with the idCustomer column in a way to show the name of client instead his id? I’ve used this HQL query

SELECT c.date, c.name Commande, cu.nameClient FROM Commande AS c, Customer AS cu WHERE cu.idCustomer = c.idCustomer

But I have no idea about the List<> type that I need to use to get the result/

Answer 1

If you map the reverse relation in the Commande entity …

public class Commande {
    ...

    @ManyToOne(mappedBy="commande")
    private Client client;

    // getter and setter ...
}

_{(Here, mappedBy is getting the name of the @OneToMany property set up at the
other side of the relationship)}

Then after executing your query SELECT c FROM Commande c you would get a list of Commande objects, and for each one of them you could get the name of the client using: thisCommande.getClient().getName().