如何避免数据库中的重复。

'1', 'Male'
'2', 'Male'
'3', 'Female'

只保存

'1', 'Male'
'2', 'Female'

或：
只保存
国家

'1', 'UK'
    '2', 'Brazil'
    '3', 'China'

我的数据库架构：

CREATE TABLE IF NOT EXISTS `bi_person` (
        `id_person` INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
        `name` VARCHAR(50) NOT NULL,
        `last_name` VARCHAR(100) NOT NULL,
         `additional_info` VARCHAR(50) NOT NULL,
        `gender_id` VARCHAR (50) UNIQUE REFERENCES bi_gender
    ) COLLATE='utf8_bin';

--表'bi.性别'

CREATE TABLE IF NOT EXISTS `bi_gender` (
        `id_gender` INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
        `name`  VARCHAR(10) NOT NULL  
    ) COLLATE='utf8_bin';

--表'bi.country`

CREATE TABLE IF NOT EXISTS `bi_country` (
        `id_country` INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
        `name`  VARCHAR(10) NOT NULL 
    ) COLLATE='utf8_bin';

我有多对多国家和一对多性别的模型
型号：

public class Country {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="id_book")
    private Integer id;

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

    @ManyToMany(cascade = CascadeType.ALL)
    @JoinTable(name="bi_person_country", joinColumns=@JoinColumn(name="id_country"), inverseJoinColumns=@JoinColumn(name="id_person"))
    private Set<Person> persons;

模特性别：

@Table(name = "bi_gender")
@Entity
public class Gender {

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

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

个人实体：

public class Person {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="id_person")
    private Integer id;

    @Column(name = "name")
    private String name;
    @Column(name = "last_name")
    private String lastName;
    @Column(name = "additional_info")
    private String additionalInfo;

    @ManyToMany(cascade = CascadeType.ALL, mappedBy = "persons")
    private Set<Country> countries;

添加person对象：
person=人（）；

Gender gender = new Gender();

            gender.setGenderName(pepPersons.get(a).getGender());

            gender = genderRepository.save(gender);

            Country country = new Country();

            country.setCountryName(pepPersons.get(a).getCountry());

            country = countryRepository.save(country);

            person.setName(pepPersons.get(a).getFirstName());
            person.setLastName(pepPersons.get(a).getLastName());
            person.setAdditionalInfo(pepPersons.get(0).getFunction());
            person.setGender(gender);

            Set<Country> countries = new HashSet();
            countries.add(country);
            person.setCountries(countries);

            personRepository.save(person);