Spring Data and Persistence

Question 1

What is Spring Data JPA?

Answer 1

A part of Spring Data that simplifies working with JPA-based repositories by providing common CRUD operations and query methods.

Question 2

What is the @Entity annotation in JPA?

Answer 2

It marks a class as a JPA entity mapped to a database table.

Question 3

What is the role of @Repository in Spring Data?

Answer 3

It is used to indicate that the class provides CRUD or data manipulation operations on a database.

Question 4

What is the @Transactional annotation used for?

Answer 4

To manage transactions declaratively in Spring.

Question 5

How can you create a repository interface in Spring Data JPA?

Answer 5

By extending JpaRepository or CrudRepository.

Question 6

How does Spring Data JPA handle pagination?

Answer 6

Using the Pageable interface and returning Page<T> results from repository methods.</T>

Question 7

What is Lazy and Eager loading in JPA?

Answer 7

Lazy loading fetches data on demand, while Eager loading fetches all related entities upfront.

Question 8

How can you define a custom query in Spring Data JPA?

Answer 8

Using the @Query annotation in repository interfaces.

Question 9

What is the difference between save() and saveAndFlush() in Spring Data JPA?

Answer 9

save() saves an entity but may not flush it to the database immediately, while saveAndFlush() forces an immediate flush.

Question 10

What is the purpose of the @Id annotation in JPA?

Answer 10

It marks a field as the primary key for the entity.