How do you define a primary key in a JPA entity class?

How do you define a primary key in a JPA entity class?

Answer:

Explanation:

The @Id annotation in Spring Data JPA is used to define the primary key of an entity class. The primary key is a unique identifier for each entity instance, and it maps to the primary key column in the database table.

For example:

@Entity
public class User {

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

    // Getters and setters
}

In this example, the id field is annotated with @Id, indicating that it is the primary key of the User entity. The @GeneratedValue annotation specifies that the value of the primary key will be automatically generated, typically using an auto-increment strategy in the database.

The @Id annotation is essential in JPA for establishing the entity’s identity, ensuring that each instance is uniquely identifiable within the database.

Reference links:

Spring Data JPA Tutorial