Avi Block

/**
 * @Entity
 * @InheritanceType("JOINED")
 * @DiscriminatorColumn(name="event_type", type="string")
 * @DiscriminatorMap({"auction" = "Auction", "raffle" = "Raffle"})
 */
class Event {
   /**
     * @Id @Column(type="integer")
     * @GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @OneToOne(targetEntity="Organization",cascade={"persist"})
     * @JoinColumn(name="org_id", referencedColumnName="id")
     */
     private $organization;
}

class Organization {
   /**
     * @Id @Column(type="integer")
     * @GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @OneToMany(targetEntity="Event", mappedBy="organization")
     */

    private $events;

    public function getId() {
        return $this->id;
    }
}

$q = $em->createQuery('select a from Organization a where a.id = 3');

$a = $q->getResult();

$events = $a[0]->getEvents();