Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>To map one-to-one association using shared primary keys use <code>@PrimaryKeyJoinColumn</code> and <code>@MapsId</code> annotation.</p> <p>Relevant sections of the Hibernate Reference Documentation:</p> <p><a href="http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html_single/#entity-mapping-association" rel="noreferrer">PrimaryKeyJoinColumn</a> </p> <blockquote> <p>The PrimaryKeyJoinColumn annotation does say that the primary key of the entity is used as the foreign key value to the associated entity.</p> </blockquote> <p><a href="http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html_single/#entity-mapping-identifier" rel="noreferrer">MapsId</a> </p> <blockquote> <p>The MapsId annotation ask Hibernate to copy the identifier from another associated entity. In the Hibernate jargon, it is known as a foreign generator but the JPA mapping reads better and is encouraged</p> </blockquote> <p><strong><em>Person.java</em></strong></p> <pre><code>@Entity public class Person { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "person_id") private Long id; @OneToOne(cascade = CascadeType.ALL) @PrimaryKeyJoinColumn private VitalStats vitalStats; } </code></pre> <p><strong><em>VitalStats.java</em></strong></p> <pre><code>@Entity public class VitalStats { @Id @Column(name="vitalstats_id") Long id; @MapsId @OneToOne(mappedBy = "vitalStats") @JoinColumn(name = "vitalstats_id") //same name as id @Column private Person person; private String stats; } </code></pre> <p><strong>Person Database Table</strong></p> <pre><code>CREATE TABLE person ( person_id bigint(20) NOT NULL auto_increment, name varchar(255) default NULL, PRIMARY KEY (`person_id`) ) </code></pre> <p><strong>VitalStats Database Table</strong></p> <pre><code>CREATE TABLE vitalstats ( vitalstats_id bigint(20) NOT NULL, stats varchar(255) default NULL, PRIMARY KEY (`vitalstats_id`) ) </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POJPA @OneToOne with Shared ID -- Can I do this Better?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USs.alem
    1. USJoel Hudon
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POJPA @OneToOne with Shared ID -- Can I do this Better?
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COThanks, but I'm afraid this doesn't really help. You've put an id field in VitalStats in addition to the Person field, whereas I can't add a new field to the schema and have to use the FK that underlies 'person' as the PK of VitalStats. That was the whole point.
      singulars
      1. PO
      1. USMichael
    2. CONo need to add another column because of the MapById annotation on the person attribute. The exemple i post was not really clear, i modify the exemple to add more details to VitalStats (See #JoinColumn on the person attribute). I add the VitalStats and Person database table and you can see that the VitalStats table contain only a PK that is the FK for person. I think is the same as what you want? If it's not what you want can you add more details on the table layout ? @MapId has the advantage that the person entity does not need to be serializable. I updated the exemple.
      singulars
      1. PO
      1. USJoel Hudon
    3. COThat's excellent, thank you! I tried it and it worked.
      singulars
      1. PO
      1. USMichael
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload