Hibernate mapping annotations

--Ads--

Hibernate mapping annotations

In this section, you will learn about the annotations used for various mapping in Hibernate.

Given below mapping annotations under different type of mapping :

One-to-One Mapping

The worker and workerdetail have one-to-one mapping which can be symbolically shown as below :

worker----------------->workerdetail

In Worker class, do the following mapping :


@OneToOne(mappedBy = "worker", cascade = CascadeType.ALL)
private WorkerDetail workerDetail;

In WorkerDetail class, do the following mapping :


@OneToOne
@PrimaryKeyJoinColumn
private Worker worker;

One-to-Many Mapping

The employee and address table have One-to-Many relation as follows :

The Address class should have following mapping annotation :


@OneToMany(mappedBy = "address")
private Set<Employee> employees;

The mapping annotation of Employee class are given below :


@OneToMany(mappedBy = "address")
private Set<Employee> employees;

Many to Many Mapping

Many student may have register for various courses and a course may have many registered student. The Many to Many mapping between student and course table can be shown as follows:

The mapping annotation of Student class is given below:


@ManyToMany(cascade = {CascadeType.ALL})
@JoinTable(name="student_course",joinColumns={@JoinColumn(name="student_id")},inverseJoinColumns={@JoinColumn(name="course_id")})
private Set<Course> courses = new HashSet<Course>();

The Course class mapping annotation is given below :


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

NOTE : student_course table doesn't have pojo class neither it have mapping annotation needed in the above cases.

Hibernate mapping annotations