Active Records

[eluser]RobertB.[/eluser]
Hello guys,
How can I do this operation with active records.

Code:

WHERE b.cat_id = 2 OR b.state_id IS NULL

Just in case, this is how I'll like to use it.

Code:

$this->db->select('s.id, s.state, COUNT(b.is_active) AS active');
$this->db->from('states AS s');
$this->db->join('businesses AS b', 's.id = b.state_id', 'left');
$this->db->where('b.cat_id', $this->uri->segment(3), 'b.state_id', null);
$this->db->groupby('s.id')

Thanks,
Robert.