如何在Oracle 10gR2和JPA中对区分大小写和重音不敏感？

SELECT * FROM users WHERE NLS_UPPER(username) = NLS_UPPER('JohnDoe');

SELECT * FROM users WHERE NLS_COMP(username, 'JohnDoe') = 0;

String jpql = "SELECT u FROM User u WHERE u.username = :username COLLATE utf8_general_ci";
TypedQuery<User> query = entityManager.createQuery(jpql, User.class);
query.setParameter("username", "JohnDoe");

SELECT * FROM users WHERE NLSSORT(username, 'NLS_SORT=GENERIC_M') = NLSSORT('JohnDoe', 'NLS_SORT=GENERIC_M');