Codeigniter 2.1-MySQL连接

Question

I have two tables:

MENU
->id_menu
->title
->page_id
->order

PAGES
->id_page
->title
->page
->slug

This is select function:

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

Here is my problem - item in the menu can be connected with page, but also it can be solo (without connection to page). This means page_id in MENU table can be 0. If page_id is 0, I am not getting that row from above query. How can I get all items in the menu (those which are connected and those which are not connected with page )?

Answer 1

You need add the join type in ->join()

like

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

See reference manual Active Record

Answer 2

As requested from comments:

You need to use "LEFT JOIN" to retrieve partial or incomplete values from the tables.

In this case, the regular join is looking the matches between the two tables. Since there's no id 0 in one of the tables, the match can't be retrieved and the row won't be selected.

Using a LEFT JOIN (or RIGHT JOIN when appropriate, based on which one is the "incomplete" table) if the match isn't retrieved, the outcome will contain also the rows which aren't matched, with all NULLs in the other table's values

Answer 3

From Your Controller call this method in Model Say your Model Name is general_model

 $value=('menu.*, pages.id_page, pages.title AS page_title'); $joins = array ( array ( 'table' => 'pages', 'condition' => 'menu.id_page = pages.page_id', 'jointype' => 'leftouter' ), ); $where_condition=array('menu.Id '=>'Enable','restaurant.Id'=>$rest_id); $data['detail'] = $this->general_model->get_joins('menu',$value,$joins,$where_condition,'menu.Id','asc')->result(); 

here $where_condition is a where condition you want to pass if u want to remove you can remove it from function.,And Last two parameters are orderby

Simply use this function in your Model For Join

 public function get_joins($table,$value,$joins,$where,$order_by,$order) { $this->db->select($value); if (is_array($joins) && count($joins) > 0) { foreach($joins as $k => $v) { $this->db->join($v['table'], $v['condition'], $v['jointype']); } } $this->db->order_by($order_by,$order); $this->db->where($where); return $this->db->get($table); }