need help with sql query using Active Record plz

[eluser]davidbehler[/eluser]

Code:

$this->db->select('tariffdesc');
$this->db->select('SUM(duration) AS duration', FALSE);
$this->db->select('COUNT(id_call) AS id_call', FALSE);
$this->db->from('calls');
$this->db->where('caller_id', 'moh');
$this->db->group_by('tariffdesc');

have fun