[FX.php List] Query field for content empty

[Gjermund Gusland Thorsen]

I have tried these with no luck

$q->AddDBParam( 'field', '', 'eq' );
$q->AddDBParam( 'field', '""', 'eq' );
$q->AddDBParam( 'field', '==""' );
$q->AddDBParam( 'field', '=""' );

How am I supposed to query for field with empty value?

ggt667