我正在练习Hibernate，我正在将数据填充到数据库中，但是有一个额外的列正在与JoinColumn沿着添加
实体：移动的类-

@Entity
public class Mobile {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer mobileId;
    
    @Basic
    private String mobileName;
    
    @OneToOne(cascade = CascadeType.ALL)
    private Sim sim;
    
    public Mobile() {
        super();
        // TODO Auto-generated constructor stub
    }
    public Mobile(Integer mobileId, String mobileName, Sim sim) {
        super();
        this.mobileId = mobileId;
        this.mobileName = mobileName;
        this.sim = sim;
    }
    public Integer getMobileId() {
        return mobileId;
    }
    public void setMobileId(Integer mobileId) {
        this.mobileId = mobileId;
    }
    public String getMobileName() {
        return mobileName;
    }
    public void setMobileName(String mobileName) {
        this.mobileName = mobileName;
    }
    public Sim getSim() {
        return sim;
    }
    public void setSim(Sim sim) {
        this.sim = sim;
    }
}

public class String {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer simId;

@Column(name="name")
private String simName;

@OneToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "mobile")
private Mobile mobile;

public Sim() {
    super();
    // TODO Auto-generated constructor stub
}

public Sim(Integer simId, String simName, Mobile mobile) {
    super();
    this.simId = simId;
    this.simName = simName;
    this.mobile = mobile;
}

public Integer getSimId() {
    return simId;
}

public void setSimId(Integer simId) {
    this.simId = simId;
}

public String getSimName() {
    return simName;
}

public void setSimName(String simName) {
    this.simName = simName;
}

public Mobile getMobile() {
    return mobile;
}

public void setMobile(Mobile mobile) {
    this.mobile = mobile;
}

}

Main Class-

public class Main { public static void main（String[] args）{ SessionFactory sessionFactory = new Configuration（）.configure（）.buildSessionFactory（）;

Mobile mobile = new Mobile();
    mobile.setMobileName("Nokia");
    Sim sim = new Sim();
    sim.setSimName("Aircel");
    mobile.setSim(sim);
    sim.setMobile(mobile);
    
    Session session = sessionFactory.openSession();
    session.save(mobile);
    
    Transaction tx = session.beginTransaction();
    tx.commit();
    
    session.close();
    sessionFactory.close();
}

}

Output:
mobile table:

    mobileId|mobileName|sim_simId|
    --------+----------+---------+
           2|Nokia     |        2|

sim table:

    simId|name  |mobile_mobileId|mobile|
    -----+------+---------------+------+
        2|Aircel|               |     2|


Why is the column mobile_mobileId being generated?