$this->db->insert($_POST); Is there a way to exclude one field?

[eluser]0plus1[/eluser]
I have a form inizialized like this:

Code:

<?=form_open('xyz/submit');?>

I have a field that I don't need to put into the database but using:

Code:

$this->db->insert('db',$_POST);

CI tries to query it.. now I wonder, is there a way to avoid this? Or do I have to make it like this?

Code:

$data = array('woof' => $_POST['woof'] , 'meow' => $_POST['meow']);

Thanks