set NULL with Query.setParameter

jenser212 · **Joined:** Sun Aug 06, 2006 4:12 am **Posts:** 4

Hi all,

is there a way to set NULL with Query.setParameter in Hibernate 3.1.3?

Code:

System.out.println(
      createQuery("from Table t where w.field = null")
      .list()
      .size()
);

>> Returns 2 rows

Code:

System.out.println(
      createQuery("from Table t where t.field = :param")
      .setParameter("param", null)
      .list()
      .size()
);

>> Returns 0 rows

Maybe there is an constant to use?

Best regards,
Jens

kheston · **Joined:** Fri Sep 02, 2005 6:03 pm **Posts:** 13

Jens,

You've probably already thought of this, but just in case...

Here's a kludge that will keep you operating until a better answer comes:

Code:

if(obj == null) {
  qry = createQuery("from Table t where w.field = null");
}else{
  qry = createQuery("from Table t where t.field = :param");
  qry.setParameter("param", obj);
}

int size = qry.list().size();

max · **Posted:** Sun Aug 06, 2006 12:59 pm

guys ;)

"field = null" is always false in sql and hql which both uses the same ternary logic.

you should check for null by "field is null".

jenser212 · **Joined:** Sun Aug 06, 2006 4:12 am **Posts:** 4

max wrote:

guys ;)

"field = null" is always false in sql and hql which both uses the same ternary logic.

you should check for null by "field is null".

Are you shure?

Code:

createQuery("from Table t where t.field = null")

and

Code:

createQuery("from Table t where t.field is null")

return the same result...

jenser212 · **Joined:** Sun Aug 06, 2006 4:12 am **Posts:** 4

kheston,

that's the way I go up to now...
But it's a good idea. ;-)

max · **Posted:** Sun Aug 06, 2006 4:06 pm

i'm sure that in SQL x = null does not evalute to what you think it does.

look it up if you don't belive me.

max · **Posted:** Sun Aug 06, 2006 4:09 pm

btw. just to be correct, x = null actually doesn't evaluate to either true or false...anyway look up sql, null and ternary logic.