Difference between CRUDRepository and JPARepository.

Question

Accepted Answer

CrudRepository and JpaRepository are both Spring Data repository interfaces, but JpaRepository extends CrudRepository (via PagingAndSortingRepository) to add JPA-specific and pagination-related capabilities on top of the basic CRUD operations.

Key Points:
• CrudRepository provides the fundamentals: save(), findById(), findAll(), deleteById(), count(), and existsById().
• JpaRepository inherits everything from CrudRepository and PagingAndSortingRepository, adding methods like flush(), saveAndFlush(), deleteInBatch(), and findAll(Pageable) / findAll(Sort).
• Because JpaRepository extends CrudRepository, you never lose any CRUD functionality by choosing it.
• In practice, most Spring Boot projects default to JpaRepository since pagination, sorting, and batch operations are commonly needed.
• CrudRepository can be a good, more minimal choice for very simple repositories or non-JPA Spring Data modules (like MongoDB) where JPA-specific methods don't apply.

Example:
A UserRepository that only ever needs save() and findById() could extend CrudRepository, but the moment the application needs a paged listing of users sorted by name, it needs to extend JpaRepository instead to get access to findAll(Pageable).

Code Example:
```
public interface UserRepository extends JpaRepository {
    // inherits save(), findById(), findAll(Pageable), flush(), etc.
}
```

Interview Tip:
A concise interview answer is:

"JpaRepository extends CrudRepository, so it includes all the basic CRUD methods plus JPA-specific extras like flushing changes, batch deletes, and pagination/sorting support via findAll(Pageable). I default to JpaRepository in Spring Boot projects since I rarely know upfront that I'll never need pagination or batching."