@ManyToMany relationship in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a many-to-many relationship in a Spring Boot entity.

Spring Boot

import jakarta.persistence.*;
import java.util.*;

@Entity
public class Student {

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

    private String name;

    @[1]
    private Set<Course> courses = new HashSet<>();

    // getters and setters
}

Drag options to blanks, or click blank then click option'

AOneToMany

BOneToOne

CManyToMany

DManyToOne

Attempts:

3 left

💡 Hint

Common Mistakes

Using @OneToMany instead of @ManyToMany

Forgetting to import the correct annotation

Using @ManyToOne which is for many-to-one relationships

The @ManyToMany annotation defines a many-to-many relationship between entities.

2fill in blank

medium

Complete the code to specify the join table for the many-to-many relationship.

Spring Boot

import jakarta.persistence.*;
import java.util.*;

@Entity
public class Student {

    @ManyToMany
    @[1](
        name = "student_course",
        joinColumns = @JoinColumn(name = "student_id"),
        inverseJoinColumns = @JoinColumn(name = "course_id")
    )
    private Set<Course> courses = new HashSet<>();

    // getters and setters
}

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AJoinTable

BEntity

CJoinColumn

DTable

Attempts:

3 left

💡 Hint

Common Mistakes

Using @JoinColumn instead of @JoinTable for the join table

Using @Table which is for entity tables, not join tables

The @JoinTable annotation defines the join table and join columns for a many-to-many relationship.

3fill in blank

hard

Fix the error in the code to correctly map the many-to-many relationship inverse side.

Spring Boot

import jakarta.persistence.*;
import java.util.*;

@Entity
public class Course {

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

    private String title;

    @ManyToMany(mappedBy = "[1]")
    private Set<Student> students = new HashSet<>();

    // getters and setters
}

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Acourses

Bstudents

Ctitle

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'students' instead of 'courses' in mappedBy

Using a field name that does not exist

The mappedBy attribute should match the name of the collection in the owning entity, which is courses in Student.

4fill in blank

hard

Fill both blanks to complete the code for the join table with cascade and fetch type.

Spring Boot

import jakarta.persistence.*;
import java.util.*;

@Entity
public class Student {

    @ManyToMany(cascade = CascadeType.[1], fetch = FetchType.[2])
    @JoinTable(
        name = "student_course",
        joinColumns = @JoinColumn(name = "student_id"),
        inverseJoinColumns = @JoinColumn(name = "course_id")
    )
    private Set<Course> courses = new HashSet<>();

    // getters and setters
}

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AALL

BEAGER

CLAZY

DREMOVE

Attempts:

3 left

💡 Hint

Common Mistakes

Using FetchType.EAGER which loads immediately and can cause performance issues

Using CascadeType.REMOVE only instead of ALL

CascadeType.ALL applies all cascade operations. FetchType.LAZY delays loading related entities until needed.

5fill in blank

hard

Fill all three blanks to complete the bidirectional many-to-many relationship with proper annotations and collection types.

Spring Boot

import jakarta.persistence.*;
import java.util.*;

@Entity
public class Course {

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

    private String title;

    @ManyToMany(mappedBy = "[1]", cascade = CascadeType.[2], fetch = FetchType.[3])
    private Set<Student> students = new HashSet<>();

    // getters and setters
}

Drag options to blanks, or click blank then click option'

Acourses

BALL

CLAZY

DList

Attempts:

3 left

💡 Hint

Common Mistakes

Using List instead of Set for many-to-many collections

Incorrect mappedBy value

Using FetchType.EAGER unnecessarily

The mappedBy should be 'courses' to match the owning side. Cascade type ALL applies all cascade operations. Fetch type LAZY delays loading until needed.