Hibernate - Join query

Question

I have two classes:

@Entity
public class Tick {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;

@ManyToOne(optional = false)
@JoinColumn(name = "elitesystem_id", referencedColumnName = "id")
private EliteSystem eliteSystem;

private Date createDate;

@ManyToOne(optional = true)
@JoinColumn(name = "commander_id", referencedColumnName = "id")
private Commander commander;

private String address;

and

@Entity
public class Note {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;

@ManyToOne(optional = true)
@JoinColumn(name = "tick_id", referencedColumnName = "id")
private Tick tick;

private String text;

private Date createDate;

I want to select all ticks and get notes if there are any:

    Query query = session.createQuery("select t, n from Note n right join n.tick t where t.commander.name = '123'");
    List<Object[]> list = query.list();

This returns only Tick objects. What is the correct approach to get the Note information as well in 1 single query? I could put a reference to a Note into the Tick class, but this doesnt sound right, as there are only a few notes, so the column in the Tick table would mostly be empty.

Mailkov · Accepted Answer · 2014-12-01 11:42:04Z

1

Create a New class for example:

public class TickNote {
    private Tick tick;
    private Note note;

    public TickNote(Tick tick,Note note){
        this.tick=tick;
        this.note=note;

Then your query is:

Query query = session.createQuery("select NEW TickNote(t, n) from Note n right join n.tick t where t.commander.name = '123'");
    List<TickNote> list = query.list();

answered Dec 1, 2014 at 11:42

Mailkov

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