public function fetch_user_added_ads_display() {
    $this->db->select('*');
    $this->db->from('user_added_ads');
    $this->db->join('media_ads','media_ads.user_added_ads_id=user_added_ads.user_added_ads_id');
    $this->db->group_by('user_added_ads.user_added_ads_id');
    $this->db->limit('3');
    $q=$this->db->get();

    return $q->result();
}

Hello friends can anyone please suggest me how can i fetch data from database, that is i need from 4th row to 8th row,so how can i do it in codeigniter