调用未定义的方法CI_DB_mysql_driver :: get_compiled_select（）？

Question

I've the following sql active record query which is giving this error. I have inner select queries so that why I tried to use this method that i found on google but it's giving error that get_complied_select is not defined. How to solve this error or is there any other better way to write following queries? Thanks!

        $this->db->select('id_dem');
    $this->db->from('dem_demos');
    $this->db->where('id_dem IN (".implode("," ,$id_v).") OR maindemo_dem IN (".implode(",",$id_v).")');
    $innermost_query = $this->db->get_compiled_select();

    $this->db->select('COUNT(demo_vis) as tot_visits');
    $this->db->from('sta_views');
    $this->db->where('countvisit_wis != "N" AND demo_vis IN $innermost_query AND date_vis BETWEEN 
    ".$date_s." AND ".$date_e."');
    $first_query = $this->db->get_compiled_select();

    $this->db->select('COUNT(demo_vis) as tot_visits');
    $this->db->from('sta_views');
    $this->db->where('countvisit_wis != "N"
                  AND demo_vis IN $innermost_query AND date_vis BETWEEN ".$date_s." AND ".$date_e." AND 
                  invited_vis = 0');
    $second_query = $this->db->get_compiled_select();

    $this->db->select('COUNT(demo_vis) as tot_visits');
    $this->db->from('sta_views');
    $this->db->where('countvisit_wis != "N"
                  AND demo_vis IN $innermost_query AND date_vis BETWEEN ".$date_s." AND ".$date_e." AND 
                  invited_vis > 0');
    $third_query = $this->db->get_compiled_select();

    $this->db->select('COUNT(conversion_vis)');
    $this->db->from('sta_views');
    $this->db->where('countvisit_wis != "N"
                  AND demo_vis IN $innermost_query AND date_vis BETWEEN ".$date_s." AND ".$date_e." AND 
                  invited_vis = 0 AND conversion_vis = 1');
    $fourth_query = $this->db->get_compiled_select();

    $this->db->select('COUNT(buy_vis)');
    $this->db->from('sta_views');
    $this->db->where('countvisit_wis != "N"
                  AND demo_vis IN $innermost_query AND date_vis BETWEEN ".$date_s." AND ".$date_e." AND 
                  buy_vis = 1');
    $fifth_query = $this->db->get_compiled_select();

    $this->db->select('COUNT(distinct session_vis) as unique_visits');
    $this->db->from('sta_views');
    $this->db->where('countvisit_wis != "N"
                  AND demo_vis IN $innermost_query AND date_vis BETWEEN ".$date_s." AND ".$date_e."');
    $sixth_query = $this->db->get_compiled_select();

    $query  = $this->db->select('$first_query as total_views, $second_query as website_views, $third_query as demosent_views,
    $fourth_query as website_conversions, $fifth_query as buy_now_clicks, $$sixth_query as unique_views');
    if ($query->num_rows() > 0){
        return $query->row_array();
    }else{
        return FALSE;
    }