I need a bit of help converting this SQL to CI Active Record format

[eluser]WanWizard[/eluser]
Something like

Code:

$this->db->select('root.name AS root_name, down1.name AS down1_name, down2.name AS down2_name, down3.name AS down3_name');
$this->from('categories root');
$this->db->join('categories down1', 'down1.parentid = root.id', 'LEFT OUTER');
$this->db->join('categories down2', 'down2.parentid = down1.id', 'LEFT OUTER');
$this->db->join('categories down3', 'down3.parentid = down2.id', 'LEFT OUTER');
$this->db->where('root.parentid', NULL);
$this->db->order_by('root_name', 'ASC');
$this->db->order_by('down1_name', 'ASC');
$this->db->order_by('down2_name', 'ASC');
$this->db->order_by('down3_name', 'ASC');
$query = $this->db->get();