Codeigniter - left join tables - mysql

Question

i have a table for my sql like this :
result_podium
id_result_podium
id_race
id_rider
position
point
and
result_dnf
id_result_dnf
id_race
id_rider
So what im trying to do is to join those two table and shown it as one, and here is the result and what i have tried so far :
Attempt 1 :
$this->db->select_sum('result_podium.point');
$this->db->select('riders.name AS rider_name, teams.name AS team_name');
$this->db->from('result_podium');
$this->db->join('riders','riders.id_rider = result_podium.id_rider');
$this->db->join('result_dnf','result_dnf.id_rider = riders.id_rider', 'left');
$this->db->join('teams','teams.id_team = riders.id_team');
$this->db->where('riders.is_deleted','0');
$this->db->order_by("SUM(result_podium.point) DESC");
$this->db->group_by(array('result_podium.id_rider','result_dnf.id_rider'));
$query = $this->db->get();
return $query->result();
And the result is something like this :
No
rider
point
1
Nick
10
2
A
5
3
D
5
4
CC
4
5
B
4
it managed to get data from table result_podium but not managed to join data from table result_dnf, and here is my another attempt :
Attempt 2 :
$this->db->select_sum('result_podium.point');
$this->db->select('result_dnf.*, riders.name AS rider_name, teams.name AS team_name');
$this->db->from('result_dnf');
$this->db->join('riders','riders.id_rider = result_dnf.id_rider');
$this->db->join('teams','teams.id_team = riders.id_team');
$this->db->join('result_podium','result_podium.id_rider = riders.id_rider', 'left');
$this->db->where('riders.is_deleted','0');
$this->db->order_by("SUM(result_podium.point) DESC");
$this->db->group_by(array('result_dnf.id_rider','result_podium.id_rider'));
and here is the result :
No
rider
point
1
A
5
2
D
5
3
B
4
4
CC
4
5
Bri
6
Brum
the point data forBri and Brum, is null because they came from result_dnf, but i did not managed to get Nick data from result_podium.
And here what i was expecting for the data to shown in my view :
No
rider
point
1
Nick
10
2
A
5
3
D
5
4
CC
4
5
B
4
5
Bri
6
Brum
is there a way to join those two table?, anyhelp is really appreciated thank you!.