Custom findStudentByEmail function will fetch student information using student email address.

Application.java

/*          FIND SOMEONE WITH GIVEN EMAIL ADDRESS
             * ==========================================================================*/
            studentRepository
                    .findStudentByEmail("ahmed.ali@gmail.com")
                    .ifPresentOrElse(
                            System.out::println,
                            ()-> System.out.println("Student with email ahmed.ali@gmail.com not found"));

StudentRepository

public interface StudentRepository extends JpaRepository<Student, Long> {

    Optional<Student> findStudentByEmail(String email);
}