EOQualifier - Query from database - "not in" or "not exists"

Hi,
Anybody know how can I implement "not exists" part of my query in
EOQualifier?
I have 2 tables A and B. I want to say select * from A where A_ID not
in (select A_ID from B).
What can qualifier1 be?

EOQualifier secQual = new EOAndQualifier( new NSArray(new Object[]
{qualifier1}));
fetchSpec = new EOFetchSpecification("A", secQual, null);
fetchSpec.setRefreshesRefetchedObjects(true);
pickList = new NSMutableArray
editingContext.objectsWithFetchSpecification(fetchSpec));

Thanks
  


 		
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