2.7.1. @ManyToOne

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`@ManyToOne` is the most common association, having a direct equivalent in the relational database as well (e.g. foreign key),
and so it establishes a relationship between a child entity and a parent.

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<div id="associations-many-to-one-example" class="exampleblock">
<div class="title">Example 125. `@ManyToOne` association</div>
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<pre class="prettyprint highlight">`@Entity(name = "Person")
public static class Person {

    @Id
    @GeneratedValue
    private Long id;

    public Person() {
    }
}

@Entity(name = "Phone")
public static class Phone {

    @Id
    @GeneratedValue
    private Long id;

    @Column(name = "`number`")
    private String number;

    @ManyToOne
    @JoinColumn(name = "person_id",
            foreignKey = @ForeignKey(name = "PERSON_ID_FK")
    )
    private Person person;

    public Phone() {
    }

    public Phone(String number) {
        this.number = number;
    }

    public Long getId() {
        return id;
    }

    public String getNumber() {
        return number;
    }

    public Person getPerson() {
        return person;
    }

    public void setPerson(Person person) {
        this.person = person;
    }
}`</pre>
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<pre class="prettyprint highlight">`CREATE TABLE Person (
    id BIGINT NOT NULL ,
    PRIMARY KEY ( id )
)

CREATE TABLE Phone (
    id BIGINT NOT NULL ,
    number VARCHAR(255) ,
    person_id BIGINT ,
    PRIMARY KEY ( id )
 )

ALTER TABLE Phone
ADD CONSTRAINT PERSON_ID_FK
FOREIGN KEY (person_id) REFERENCES Person`</pre>
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Each entity has a lifecycle of its own. Once the `@ManyToOne` association is set, Hibernate will set the associated database foreign key column.

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<div id="associations-many-to-one-lifecycle-example" class="exampleblock">
<div class="title">Example 126. `@ManyToOne` association lifecycle</div>
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<pre class="prettyprint highlight">`Person person = new Person();
entityManager.persist( person );

Phone phone = new Phone( "123-456-7890" );
phone.setPerson( person );
entityManager.persist( phone );

entityManager.flush();
phone.setPerson( null );`</pre>
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<pre class="prettyprint highlight">`INSERT INTO Person ( id )
VALUES ( 1 )

INSERT INTO Phone ( number, person_id, id )
VALUES ( '123-456-7890', 1, 2 )

UPDATE Phone
SET    number = '123-456-7890',
       person_id = NULL
WHERE  id = 2`</pre>
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