objectdb select where query - where-clause

Question

I attempt to select some instance using where clause
public static List<RSSItem> getRSSItem(int x1, int x2) {
EntityManagerFactory emf = DBHandler.getEmf();
EntityManager em = DBHandler.getEm(emf);
String query =
"SELECT items FROM RSSItem items "
+ "WHERE items.id <= :x1 AND "
+ "items.id >= :x2";
List<RSSItem> results =
(List<RSSItem>) em.createQuery(query).
setParameter("x1", x1).
setParameter("x2", x2).
getResultList();
return results;
}
the RSSItem attributes :
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
String title;
String link;
String description;
String pubdate;
String content;
HashMap<String, Integer> keyword = new HashMap();
HashMap<String, Integer> keywordBefore = new HashMap();
// TreeMap <String, Integer> keyword = new TreeMap();
String feed;
the problem is it always return a list with 0 size. what's wrong with my select query?

Answer 1

With the values x1 = 1 and x2 = 500, the query turns into...
SELECT items FROM RSSItem items
WHERE items.id <= 1
AND items.id >= 500
Since no id's are less or equal to 1 and greater or equal to 500 at the same time, the query will give no hits. What you want is probably;
String query =
"SELECT items FROM RSSItem items "
+ "WHERE items.id >= :x1 AND "
+ "items.id <= :x2";
...which with your example data will find all id's between 1 and 500, inclusive.