How to query NOT NULL with Doctrine?

I have table Test:

Test:
id | name 
1  | aaa
2  | 
3  | ccc
4  | aaa
5  | 
6  | ddd

I want result where name is NOT NULL:

aaa
ccc
aaa
ddd

How can i get with:

Doctrine_Core::getTable('Test')->findBy('name', NOTNULL??) <-doesnt working

and in model with:

$this->createQuery('u')
     ->where('name = ?', NOTNULL ???) <- doesnt working
     ->execute();

Answer

Try this:

$this->createQuery('u')
     ->where('name IS NOT NULL')
     ->execute();

which is standard SQL syntax. Doctrine doesn’t convert Null values into proper sql.