@Entity
@Table(name = "countries", catalog = "librarydb")
@DynamicUpdate
@DynamicInsert
@SelectBeforeUpdate
public class Country {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    @Column(unique = true)
    private String countryName;
}

@Entity
@Table(name = "authors", catalog = "librarydb")
@DynamicUpdate
@DynamicInsert
@SelectBeforeUpdate
public class Author {
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Id
    private Long id;
    private String firstName;
    private String lastName;

    @ManyToOne
    private Country country;

}

public interface AuthorRepository extends JpaRepository<Author, Long> {}

Hibernate: select author0_.id as id1_0_, author0_.country_id as country_6_0_, author0_.first_name as first_na3_0_, author0_.last_name as last_nam4_0_, from librarydb.authors author0_
Hibernate: select country0_.id as id1_2_0_, country0_.country_name as country_2_2_0_ from librarydb.countries country0_ where country0_.id=?
Hibernate: select country0_.id as id1_2_0_, country0_.country_name as country_2_2_0_ from librarydb.countries country0_ where country0_.id=?
Hibernate: select country0_.id as id1_2_0_, country0_.country_name as country_2_2_0_ from librarydb.countries country0_ where country0_.id=?
Hibernate: select country0_.id as id1_2_0_, country0_.country_name as country_2_2_0_ from librarydb.countries country0_ where country0_.id=?
Hibernate: select country0_.id as id1_2_0_, country0_.country_name as country_2_2_0_ from librarydb.countries country0_ where country0_.id=?