Join 3 tables in a ManytoMany relationship using JpaRepository-CodePudding

since i dind't found 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

@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;
}


}




  @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;
}


}

CodePudding user response：

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;