Bdtjtk

I'm making hibernate and java project for studies and I need help.

I'm making student database where user can add student, his marks, set lesson group and subject.

When I add student with all these things(lesson group etc.) it's ok, but when I want to set the same student another mark for the same subject in result I have

look here from my phpmyadmin:

I get stucked in this moment and I don't have idea how to solve this problem.

Add Student Button

addButton.setOnAction((ActionEvent event) -> {

        if (textFieldStudentName.getText() != null && !TextFieldStudentUserName.getText().isEmpty()) {



           int selectedMark = setMark.getSelectionModel().getSelectedIndex();

            selectedMark++;

            String selectedGroup = (String) setGroup.getSelectionModel().getSelectedItem();





            Student student = new Student();

            Subject subject = new Subject();

            Marks mark = new Marks();

            Group group = new Group();



            group.setGroup_name(selectedGroup);

            mark.setMark(selectedMark);

            subject.setSubject_name(subjectField.getText());

            student.setName(textFieldStudentName.getText());

            student.setUserName(TextFieldStudentUserName.getText());

            mark.setStudent(student);

            mark.setSubject(subject);

            student.setGroup(group);





            subjectDAO.create(subject);

            groupDAO.create(group);

            studentDAO.create(student);

            marksDAO.create(mark);



            textFieldStudentName.clear();

            TextFieldStudentUserName.clear();

            subjectField.clear();



        }

    });

Student Class

@Entity

public class Student implements Serializable {



private static final long serialVersionUID = 4L;



@Id

@GenericGenerator(name = "generator", strategy = "increment")

@GeneratedValue(generator = "generator")

@Column(unique = true)

private int student_id;

@Column(length = 15, nullable = false,name="imie")

private String name;

@Column(length = 15, nullable = false,name="nazwisko")

private String UserName;





@ManyToOne(cascade = CascadeType.MERGE)

@JoinColumn(name = "group_id")

private Group group;





@OneToMany(targetEntity = Marks.class, mappedBy = "student", cascade = CascadeType.REMOVE)

private Set<Marks> marks;



public Student(int student_id, String name, String UserName, Group group, Set<Marks> marks) {

    this.student_id = student_id;

    this.name = name;

    this.UserName = UserName;

    this.group = group;

    this.marks = marks;

}



public Student(){};



public int getStudent_id() {

    return student_id;

}



public void setStudent_id(int student_id) {

    this.student_id = student_id;

}



public String getName() {

    return name;

}



public void setName(String name) {

    this.name = name;

}



public String getUserName() {

    return UserName;

}



public void setUserName(String UserName) {

    this.UserName = UserName;

}



public Group getGroup() {

    return group;

}



public void setGroup(Group group) {

    this.group = group;

}



public Set<Marks> getMarks() {

    return marks;

}



public void setMarks(Set<Marks> marks) {

    this.marks = marks;

}



public int setMark(int selectedMark) {

    return selectedMark;

}



}

Marks Class

@Entity

@Table(name = "Oceny")

public class Marks implements Serializable {

private static final long serialVersionUID = 2L;







@Id

@GenericGenerator(name = "generator", strategy = "increment")

@GeneratedValue(generator = "generator")

@Column(unique = true)

private long ocena_id;

@Column(name = "ocena")

private int mark;





@ManyToOne(cascade = CascadeType.ALL)

@GeneratedValue

@JoinColumn(name = "subject_id")

private Subject subject;



@ManyToOne(cascade = CascadeType.ALL)

@GeneratedValue

@JoinColumn(name = "student_id")

private Student student;



public Marks(long ocena_id, int mark, Subject subject, Student student) {

    this.ocena_id = ocena_id;

    this.mark = mark;

    this.subject = subject;

    this.student = student;

}

public Marks(){};



public long getOcena_id() {

    return ocena_id;

}



public void setOcena_id(long ocena_id) {

    this.ocena_id = ocena_id;

}



public int getMark() {

    return mark;

}



public void setMark(int mark) {

    this.mark = mark;

}



public Subject getSubject() {

    return subject;

}



public void setSubject(Subject subject) {

    this.subject = subject;

}



public Student getStudent() {

    return student;

}



public void setStudent(Student student) {

    this.student = student;

}

I except to see XYZ with multiple marks and no duplications for subject, lesson group and student.
how I want to see in database
I made this manually in simple class,but I need to do this in javafx

public class ProjektPORun {



public static void main(String args) {

    Student student1=new Student();

    student1.setName("Adam");

    student1.setUserName("Malysz");

    Student student2=new Student();

    student2.setName("Robert");

    student2.setUserName("Kubica");

    Group grupa=new Group();

    grupa.setGroup_name("LAB1");

    Subject subject=new Subject();

    subject.setSubject_name("History");

    Marks mark=new Marks();

    mark.setMark(1);

    Marks mark1=new Marks();

    mark1.setMark(2);

    Marks mark2=new Marks();

    mark2.setMark(3);



    student1.setGroup(grupa);

    mark.setStudent(student1);

    mark1.setStudent(student1);

    mark.setSubject(subject);



    student2.setGroup(grupa);

    mark1.setStudent(student2);

    mark2.setStudent(student2);

    mark1.setSubject(subject);

    mark2.setSubject(subject);



    Configuration config = new Configuration().configure("META-INF\hibernate.cfg.xml").addAnnotatedClass(Student.class).addAnnotatedClass(Group.class).addAnnotatedClass(Marks.class).addAnnotatedClass(Subject.class);

    ServiceRegistry serviceRegistry=new StandardServiceRegistryBuilder().applySettings(config.getProperties()).build();

    SessionFactory factory = config.buildSessionFactory(serviceRegistry);



    Session session = factory.openSession();



    Transaction transaction = session.beginTransaction();

    session.save(student2);

    session.save(subject);

    session.save(mark);

    session.save(mark1);

    session.save(mark2);

    session.save(grupa);

    session.save(student1);

    transaction.commit();



    session.close();

    factory.close();

    StandardServiceRegistryBuilder.destroy(serviceRegistry);



}



}