NamedQuery on a Many to Many relation with a relational table in between

I have two tables that have a relation ManyToMany and I need to do a query to do some calculations. I have the extra handicap that I have an abstract class Price that I extend from to create the concrete prices (physical presents, money presents, etc)

My problem is that the table COUPON_PRICE doesn't have an Entity so I don't really know how to do a @NamedQuery using that table.

Otherwise everything else is working fine, tables and relations created successfully.

Thank you for any assistance you can provide. :)

Here are the Entity declarations:

Coupon Entity

@Entity
@XmlAccessorType(XmlAccessType.PUBLIC_MEMBER)
@Table(name = "ACE_COUPON")
@NamedQueries({
    @NamedQuery(name = "Coupon.getAvailableBudget",
        query = "SELECT sum(r.amount) "
              + "FROM PhysicalPresent "
              + "JOIN COUPON_PRICE crp on (r.id = crp.ID_PRICE) "
              + "JOIN Coupon cr on (cr.id = crp.ID_COUPON) "
              + "WHERE cr.id = :myID;"),)
public class Coupon {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @Column(name = "ID_COUPON")
    private Integer id;

    @Column(name = "CAMPAIGN_NAME", nullable = false)
    private String campaignName;

    @Column(name = "COUPON_CODE", unique = true, nullable = false)
    private String couponCode;

    @Column(name = "STATUS", nullable = false)
    private Boolean status;

    @Column(name = "CAMPAIGN_BUDGET")
    private Double campaignBudget;

    @ManyToMany
    @JoinTable(name = "COUPON_PRICE", joinColumns =
      @JoinColumn(name = "ID_COUPON", referencedColumnName = "ID_COUPON"), inverseJoinColumns =
      @JoinColumn(name = "ID_PRICE", referencedColumnName = "ID_PRICE"))
    private Set<Price> priceThatBelongsTo;

    --constructors, getters and setters--
}

Price Entity

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public abstract class Price implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @Column(name = "ID_PRICE")
    private Integer id;

    @Column(name = "ID_PRODUCT")
    private Integer idProduct;

    --constructors, getters and setters--
}

PhysicalEntity

@Entity
@XmlAccessorType(XmlAccessType.PUBLIC_MEMBER)
@Table(name = "ACE_PHYSICAL_PRESENT")
public class PhysicalPresent extends Price {

    @Column(name = "DESCRIPTION")
    private String description;

    @Column(name = "AMOUNT")
    private Double amount;

    @ManyToMany
    @JoinTable(name = "COUPON_PRICE", joinColumns = {
      @JoinColumn(name = "ID_PRICE", referencedColumnName = "ID_PRICE") }, inverseJoinColumns = {
      @JoinColumn(name = "ID_COUPON", referencedColumnName = "ID_COUPON") })
    private Set<Coupon> couponsThatBelongsToThisPrice;

    --constructors, getters and setters--
}