php - Codeigniter 2.1 - MySQL JOIN -

i have 2 tables:

menu ->id_menu ->title ->page_id ->order  pages ->id_page ->title ->page ->slug 

this select function:

public function get_all_menu()     {         return $this->db         ->select('menu.*, pages.id_page, pages.title page_title')         ->from($this->table)         ->join('pages','id_page = page_id')         ->order_by($this->order_by)         ->get()         ->result_array();     } 

here problem - item in menu can connected page, can solo (without connection page). means page_id in menu table can 0. if page_id 0, not getting row above query. how can items in menu (those connected , not connected page )?

as requested comments:

you need use "left join" retrieve partial or incomplete values tables.

in case, regular join looking matches between 2 tables. since there's no id 0 in 1 of tables, match can't retrieved , row won't selected.

using left join (or right join when appropriate, based on 1 "incomplete" table) if match isn't retrieved, outcome contain rows aren't matched, nulls in other table's values