inner join

                $this->db->select('*');
                $this->db->from('orders');
                $this->db->join('users', 'users.id = orders.user_id');
                $query = $this->db->get();

                $result= $query->result();

                

left join

note the third parameter in the join() function

                $this->db->select('*');
                $this->db->from('orders');
                $this->db->join('users', 'users.id = orders.user_id' ,'left' );
                $query = $this->db->get();

                $result= $query->result();