使用 JpaRepository 在多对多关系中加入 3 个表

Question

Since i dind't find an answer to my problem i'm asking here. The problem is this: i have 2 classes : Student and Course, every course can have many student and every student can have many courses,( u can see the code below). What i want to do is to use a @Query in the student repository interface implemented using JpaRepository, that gives me the name of the student and the course's name that this student follows (i don't care if i need to print every name many times for each course) but i don't know how to perform the join query since che table "course_like" is present in the db but not in java (since is a set and i use the annotations for create the join tablein the db). hope u can help me

Student Entity:

@Entity
public class Student {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    
    private String name;
    
    @ManyToMany()
    @JoinTable(
            name = "course_like", 
            joinColumns = @JoinColumn(name = "student_id"), 
            inverseJoinColumns = @JoinColumn(name = "course_id"))
    private Set<Course> courses;

    public Student() {
    }

    public Student(String name, Set<Course> courses) {
        this.name = name;
        this.courses = courses;
    }

    public Student(int id, String name, Set<Course> courses) {
        this.id = id;
        this.name = name;
        this.courses = courses;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Set<Course> getCourses() {
        return courses;
    }

    public void setCourses(Set<Course> courses) {
        this.courses = courses;
    }

}

Course Entity:

@Entity
public class Course {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    
    private String name;
    
    @ManyToMany(mappedBy = "courses")
    private Set<Student> students;

    public Course(int id, String name, Set<Student> students) {
        this.id = id;
        this.name = name;
        this.students = students;
    }

    public Course(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public Course(String name, Set<Student> students) {
        this.name = name;
        this.students = students;
    }

    public Course() {

    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Set<Student> getStudents() {
        return students;
    }

    public void setStudents(Set<Student> students) {
        this.students = students;
    }

}

Answer 1

Below query should return all the student and course mapping. Hope this helps you.

select distinct s.name, c.name from Student s join s.courses c;