@Entity
@Table(name="orders")
public class Order {
 
    @Id
    private Integer ordernumber;
 
    @Basic
    private String customerId;
 
    @OneToMany(mappedBy = "order", cascade = CascadeType.ALL)
    private List orderItems = new ArrayList();
 
    public void addOrderLine(OrderLine orderLine) {
        orderItems.add(orderLine);
    }
 
    // Getters and Setters....
}
 
@Entity
@Table(name="orderlines")
public class OrderLine {
 
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer id;
 
    @ManyToOne
    @JoinColumn(name="orderid")
    private Order order;
 
    @Basic
    private Integer quantity;
 
    @ManyToOne
    @JoinColumn(name="productid")
    private Product product;
 
    // Getters and Setters....
}
 
@Entity
@Table(name = "products")
@NamedQuery(name="product.byId", query="from Product p where p.id = :id")
public class Product {
 
    @Id
    private Integer id;
 
    @Basic
    private String name;
 
    // Getters and Setters....
}