Enterprise Java Development@TOPIC@

Chapter 50. Multi-table Mapping

50.1. Multi-table Example
50.2. Summary

50.1. Multi-table Example

Figure 50.1. Multi-table Mapping Example Database Schema

create table ORMCORE_WATCH (
    id bigint not null,
    make varchar(255),
    model varchar(255),
    primary key (id)
)
create table ORMCORE_OWNER (
    cardnum varchar(255),
    NAME varchar(255),
    OWNER_ID bigint not null,
    primary key (OWNER_ID)
)
create table ORMCORE_MAKER (
    address varchar(255),
    NAME varchar(255),
    phone varchar(255),
    MAKER_ID bigint not null,
    primary key (MAKER_ID)
)
alter table ORMCORE_MAKER 
    add constraint FKB91D15CEC0CE58E2 
    foreign key (MAKER_ID) 
    references ORMCORE_WATCH
alter table ORMCORE_OWNER 
    add constraint FKB943503D985CE28 
    foreign key (OWNER_ID) 
    references ORMCORE_WATCH

Figure 50.2. Multi-table Mapping Example Entity Class

@Entity

@Table(name="ORMCORE_WATCH")

@SecondaryTables({

    @SecondaryTable(name="ORMCORE_OWNER",

        pkJoinColumns={

            @PrimaryKeyJoinColumn(name="OWNER_ID")}),

    @SecondaryTable(name="ORMCORE_MAKER",

        pkJoinColumns={

            @PrimaryKeyJoinColumn(name="MAKER_ID")})

})

public class Watch {

    @Id

    private long id;

    private String make;

    private String model;

    @Column(name="NAME", table="ORMCORE_OWNER")

    private String owner;

    @Column(table="ORMCORE_OWNER")

    private String cardnum;

    @Column(name="NAME", table="ORMCORE_MAKER")

    private String manufacturer;

    @Column(table="ORMCORE_MAKER")

    private String address;

    @Column(table="ORMCORE_MAKER")

    private String phone;

Figure 50.3. Multi-table Mapping Example orm.xml


<entity class="ejava.examples.orm.core.mapped.Watch" access="FIELD">

    <table name="ORMCORE_WATCH"/>

    <secondary-table name="ORMCORE_OWNER">

        <primary-key-join-column name="OWNER_ID"/>

    </secondary-table>

    <secondary-table name="ORMCORE_MAKER">

        <primary-key-join-column name="MAKER_ID"/>

    </secondary-table>

    <attributes>

        <id name="id"/>

        <basic name="owner">

            <column name="NAME" table="ORMCORE_OWNER"/>

        </basic>

        <basic name="cardnum">

            <column table="ORMCORE_OWNER"/>

        </basic>

        <basic name="manufacturer">

            <column name="NAME" table="ORMCORE_MAKER"/>

        </basic>

        <basic name="address">

            <column table="ORMCORE_MAKER"/>

        </basic>

        <basic name="phone">

            <column table="ORMCORE_MAKER"/>

        </basic>

    </attributes>

</entity>        

Figure 50.4. Multi-table Mapping Example Test

//leave a watch in DB to inspect
Watch watch3 = new Watch(3);
watch3.setMake("ontime3");
watch3.setModel("round-and-round3");
watch3.setOwner("john doe3");
watch3.setCardnum("123-45-67893");
watch3.setManufacturer("getter done3");
watch3.setAddress("12noon lane3");
watch3.setPhone("410-555-12123");       
em.persist(watch3);
select * from ORMCORE_WATCH
ID MAKE    MODEL
3  ontime3 round-and-round3
select * from ORMCORE_MAKER
NAME         PHONE         ADDRESS      MAKER_ID
getter done3 410-555-12123 12noon lane3 3
select * from ORMCORE_OWNER
CARDNUM      NAME      OWNER_ID
123-45-67893 john doe3 3

50.2. Summary