Question

I use hibernate 3.5.4-final. I have two JPA classes.

    @Entity
    @Table(name = "SPI_V_OP_OBJ_SUBJECT_VR")
    public class OpSubject_vr extends PersistenceEntity implements Serializable {

        private static final long serialVersionUID = 1858749317461707015L;
        /** id */
        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        @Column(name = "ID",
                nullable = false)
        private Long id;

        /** name */
        @Column(name = "F_NAME")
        private String f_name;


        /** type */
        @Column(name = "SUBJECT_TYPE")
        private String subject_type;


        /** okved */
        @ManyToMany
        @JoinTable(name = "SPI_V_OP_OBJ_SUBJECT_VR_OKVED",
                   joinColumns = {@JoinColumn(name = "OBJECT_ID",
                                              referencedColumnName = "ID",
                                              nullable = false)},
                   inverseJoinColumns = {@JoinColumn(name = "SPR_ID",
                                                     referencedColumnName = "ID",
                                                     nullable = false)})
        private List<OpSprOkved> okved_id_mult = new ArrayList<>();
}

and

@Entity
@Table(name = "SPI_V_OP_SPR_OKVED")
public class OpSprOkved extends PersistenceEntity implements Serializable {

    /** id */
    @Id
    @Column(name = "ID", nullable = false)
    private Long id;

    /** code*/
    @Column(name = "CODE")
    private String code;

    /** name*/
    @Column(name = "name")
    private String name;
}

Attribute okved_id_mult is multiple. I want to select objects OpSubject_vr with empty attribute okved_id_mult.

I tried

select ent from OpSubject_vr ent where okved_id_mult is empty; (hibernate error)

select ent from OpSubject_vr ent where okved_id_mult is null; (hibernate error)

select distinct ent from OpSubject_vr ent join ent.okved_id_mult i1 where i1.code is null;(return 0 objects)

Answer 1

1. Query is fine but you need to qualify okved_id_mult as ent.okved_id_mult.
2. It is illegal to restrict on collection attributes.
3. You need to modify the query to use left join. Then it is logically equivalent to the first query.

See the test case at https://github.com/BatooOrg/BatooJPA/tree/master/community/src/test/java/org/batoo/jpa/community/test/t2