Can someone help me to test this class?

I have to test the class, but I am not a good tester in this case. so how would you guys test this class? in relation to what ? please show me some code. Below is the method to test :)

        Query query = getSession()
                .createSQLQuery(
                        "SELECT * FROM verwaltung_benutzer WHERE email = :benutzer_email AND id != :benutzer_id")
                .setString("benutzer_email", benutzerEmail);
        if (id == null) {
            query.setLong("benutzer_id", 0);
        } else {
            query.setLong("benutzer_id", id);
        }
        return query.list().isEmpty();
    } ´´´