Hibernate MS SQL Join问题

Question

I have two tables in the clients mssql database. The first is a job table - so I created an Job entity which contains the load type and load weight and all that stuff - works fine.

My problem now is that there is a second table that includes informations about the load and unload point. The second table, I call it JEP, has a primary key consisting of several items: the type (load or unload), the zip code and the customer number.

I created an entity JobEndPoint and NetBeans also created an object representing the primary key JobEndPointPK containing all that fields.

I want to add two JobEndPoint (loadPoint and unloadPoint) to my Job entity. My problem is now: how do I annotate that in Hibernate? In my opinion it is an @OneToOne relation ship. It would be perfect if I could specify a SELECT statement like SELECT * FROM JEP WHERE type="load" AND customer_nr="123" AND zip_code="123 ...". Is that possible with Hibernate?

Thanks for your help!

Regeards,

Marco

---

Here are the Entities:

@Entity
@Table(name = "Auftragsdaten", catalog = "...", schema = "dbo")
public class Job implements Comparable<Object>, Serializable {

    private static final long serialVersionUID = 4285871251915951149L;

    @Id
    @Basic(optional = false)
    @Column(name = "`id`", nullable = false)
    int id;

    @Column(name = "`AufNr`", nullable=false)
    int jobId;

    @Transient
    List<Integer> jobsAdded;

    @Column(name = "`Beladedatum`", nullable=false)
    @Temporal(TemporalType.DATE)
    Date loadDate;

    @Column(name = "`Beladezeit`")
    @Temporal(TemporalType.TIME)
    Date loadTimeFrom;

    @Transient
    Date loadTimeTo;

    @Column(name = "`Entladedatum`", nullable=false)
    @Temporal(TemporalType.DATE)
    Date unloadDate;

    @Column(name = "`Entladezeit Beginn`")
    @Temporal(TemporalType.TIME)
    Date unloadTimeFrom;

    @Column(name = "`Entladezeit Ende`")
    @Temporal(TemporalType.TIME)
    Date unloadTimeTo;

    @Transient
    List<JobEndPoint> froms;

    @OneToOne
    @JoinColumns ({
        @JoinColumn(name="`Beladetyp`", referencedColumnName = "`Ladetyp`", insertable = false, updatable = false),
        @JoinColumn(name="`AbsNr`", referencedColumnName = "`KundenNr`", insertable = false, updatable = false),
        @JoinColumn(name="`Verkehrsart`", referencedColumnName = "`VerkArt`", insertable = false, updatable = false),
        @JoinColumn(name="`von LKZ`", referencedColumnName = "`LKZ`", insertable = false, updatable = false),
        @JoinColumn(name="`von PLZ`", referencedColumnName = "`PLZ`", insertable = false, updatable = false)
    })
    JobEndPoint fromPoint;

    @Transient
    JobEndPoint toPoint;

    @Column(name = "`Verkehrsart`", length = 10, nullable=false)
    @Enumerated
    JobType type;

    @Column(name = "`Anzahl Paletten CCG1`")
    int numberCCG1;

    @Column(name = "`Anzahl Paletten CCG2`")
    int numberCCG2;

    @Transient
    int numberFullContainer;

    @Transient
    int numberEmptyContainer;

    @Column(name = "`Anzahl Container`")
    int numberContainer;

    @Column(name = "`Anz Stellplätze`")
    int numberUnits;

    @Column(name = "`Bruttogewicht`", nullable=false)
    int loadWeight;

    @ManyToOne
    @JoinColumn(name="`Kühlkennzeichen`")
    CoolingCode coolingCode;
}

@Entity
@Table(name = "BES", catalog = "...", schema = "dbo")
public class JobEndPoint implements Serializable {

    private static final long serialVersionUID = 1017986852824783744L;

    @Id
    protected JobEndPointPK jobEndPointPK;

    (...)
}

@Embeddable
public class JobEndPointPK implements Serializable {

    @Basic(optional = false)
    @Column(name = "`Ladetyp`", nullable = false, length = 50)
    @Enumerated
    EndPointType type;

    @Basic(optional = false)
    @Column(name = "`KundenNr`", nullable = false)
    int customerId;

    @Basic(optional = false)
    @Column(name = "`VerkArt`", nullable = false, length = 10)
    @Enumerated
    JobType jobType;

    @Basic(optional = false)
    @Column(name = "`LKZ`", nullable = false, length = 3)
    String countryCode;

    @Basic(optional = false)
    @Column(name = "`PLZ`", nullable = false, length = 7)
    String zipCode;
}

Answer 1

In general, I would recommend using a generated internal primary key instead of the composite key. However, if you need to stick with your composite key, here are some ideas that hopefully help.

I understand that JobEndPointPK is implemented as an identifier component (see the Hibernate Reference, chapter 8.4 ). Note: it is critical that it implements the equals and hashCode` methods correctly, as Hibernate relies on these.

Updated: Provided that your JobEndPoint and JobEndPointPK looks something like this:

@Embeddable
class JobEndPointPK {
    @Column(name = "type", nullable = false)
    @Enumerated
    EndPointType type;

    @Column(name = "zipCode", nullable = false)
    String zipCode;

    @Column(name = "customerNumber", nullable = false)
    int customerId;

    // equals, hasCode, getters, setters etc.
}

@Entity
class JobEndPoint {
    @Id
    private JobEndPointPK key;

    // getters, setters etc.
}

The mapping annotation would be something like:

@Entity
class Job {
    @OneToOne
    @JoinColumns ({
        @JoinColumn(name="loadPointType", referencedColumnName = "type"),
        @JoinColumn(name="loadPointZip", referencedColumnName = "zipCode"),
        @JoinColumn(name="loadPointCust", referencedColumnName = "customerNumber")
    })
    private JobEndPoint loadPoint;
    // similarly for unloadPoint
    // other properties
}

The example is adapted from here .

I am not sure how to deal with JobEndPointPK.type though, as for loadPoint it is obviously Load and for unloadPoint , Unload , so you most probably don't want to store it separately in the DB. My gues is that you can specify the value with the @Formula annotation, but I haven't seen any concrete example for this.

Note that all this code is purely experimental, I haven't tested it.

There are other variations on the theme. For more details, see the section "Composite keys with annotations" in Chapter 8 of Java Persistence with Hibernate .