Which JPA annotation is used to define a many-to-many relationship?

Java MCQ: Which JPA annotation is used to define a many-to-many relationship?

Answer:

Explanation:

The @ManyToMany annotation is used to define a many-to-many relationship in JPA. This type of relationship means that multiple instances of one entity can be associated with multiple instances of another entity. The @ManyToMany annotation is typically used on both sides of the relationship, with a join table used to manage the associations.

Here’s an example:

@Entity
public class Student {
    @Id
    private Long id;

    @ManyToMany
    @JoinTable(name = "student_course",
               joinColumns = @JoinColumn(name = "student_id"),
               inverseJoinColumns = @JoinColumn(name = "course_id"))
    private List<Course> courses;

    private String name;

    // Getters and setters
}

In this example, the Student entity has a many-to-many relationship with the Course entity, meaning that a student can be enrolled in multiple courses, and a course can have multiple students. The @JoinTable annotation specifies the join table that manages this relationship.

Many-to-many relationships are common in relational databases, and they are easily represented in JPA using the @ManyToMany annotation.

Reference links:

https://www.rameshfadatare.com/learn-java-programming/
https://www.javaguides.net/p/java-tutorial-learn-java-programming.html