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次の表があります。

CREATE TABLE IF NOT EXISTS `omc_schedule` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `trainer_id` int(11) NOT NULL,
  `course` varchar(255) NOT NULL,
  `capacity` int(11) NOT NULL,
  `active` tinyint(1) NOT NULL DEFAULT '1',
  `parentid` int(10) NOT NULL,
  `order` int(11) NOT NULL,
  `booked` int(5) NOT NULL,
  `type` varchar(255) NOT NULL,
  PRIMARY KEY (`id`)
) ...

次の関数を使用して、配列ツリーを生成できます。

 function generateTree(&$tree, $parentid = 0) {
    $this->db->select('*');
    $this->db->where ('parentid',$parentid);
$this->db->where ('active','1');
    $this->db->order_by('order asc, parentid asc');
     $res = $this->db->get('omc_schedule');
     if ($res->num_rows() > 0) {
        foreach ($res->result_array() as $r) {
    // push found result onto existing tree
            $tree[$r['id']] = $r;
            // create placeholder for children
            $tree[$r['id']]['children'] = array();
            // find any children of currently found child
            $this->generateTree($tree[$r['id']]['children'],$r['id']);
         }     
     }
      $res->free_result();
      return $tree;
 }

ここで、トレーナー テーブルに参加して、トレーナーの名前を取得したいと考えています。

CREATE TABLE IF NOT EXISTS `omc_trainer` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `trainer_name` varchar(50) NOT NULL,
  `trainer_image` varchar(100) NOT NULL,
  `video_url` text NOT NULL,
  `desc` text NOT NULL,
  PRIMARY KEY (`id`)
)

さまざまな方法で参加しようとしましたが、すべての配列でトレーナーの名前を取得できません。

JOIN を使用して再帰関数でトレーナーの名前を取得する方法はありますか?

上記の関数は CodeIgniter ですが、無視してください。

前もって感謝します。

4

1 に答える 1

2

データベースに対して 1 回の呼び出しを行い、ツリー/サブツリーを返す方がはるかに効率的で、アプリ コードをクリーンに保つことができます。

以下は、あなたが興味を持っていると思われるものを確認するための例です:

完全なスクリプトはこちら: http://paste.pocoo.org/show/274386/

-- TABLES

drop table if exists trainer;
create table trainer
(
trainer_id smallint unsigned not null auto_increment primary key,
name varchar(255) not null
)
engine=innodb;

drop table if exists schedule;
create table schedule
(
sched_id smallint unsigned not null auto_increment primary key,
trainer_id smallint unsigned null,
name varchar(255) not null,
parent_sched_id smallint unsigned null,
key schedule_parent_idx(parent_sched_id),
key schedule_trainer_idx(trainer_id)
)
engine=innodb;


-- STORED PROCEDURES

drop procedure if exists schedule_hier;

delimiter #

create procedure schedule_hier
(
in p_sched_id smallint unsigned
)
begin

declare v_done tinyint unsigned default 0;
declare v_depth smallint unsigned default 0;

create temporary table hier(
 parent_sched_id smallint unsigned, 
 sched_id smallint unsigned, 
 depth smallint unsigned default 0
)engine = memory;

insert into hier select parent_sched_id, sched_id, v_depth from schedule where sched_id = p_sched_id;

/* http://dev.mysql.com/doc/refman/5.0/en/temporary-table-problems.html */

create temporary table tmp engine=memory select * from hier;

while not v_done do

    if exists( select 1 from schedule p inner join hier on p.parent_sched_id = hier.sched_id and hier.depth = v_depth) then

        insert into hier 
            select p.parent_sched_id, p.sched_id,   v_depth + 1 from schedule p 
            inner join tmp on p.parent_sched_id = tmp.sched_id and tmp.depth = v_depth;

        set v_depth = v_depth + 1;          

        truncate table tmp;
        insert into tmp select * from hier where depth = v_depth;

    else
        set v_done = 1;
    end if;

end while;

select 
 s.sched_id,
 s.name as schedule_name,
 p.sched_id as parent_sched_id,
 p.name as parent_schedule_name,
 t.trainer_id,
 t.name as trainer_name,
 hier.depth
from 
 hier
inner join schedule s on hier.sched_id = s.sched_id
inner join schedule p on hier.parent_sched_id = p.sched_id
inner join trainer t on s.trainer_id = t.trainer_id
order by
 hier.depth, hier.sched_id;

drop temporary table if exists hier;
drop temporary table if exists tmp;

end #

delimiter ;

-- TEST DATA

insert into trainer (name) values ('trainer 1'),('trainer 2'),('trainer 3');

insert into schedule (name, trainer_id, parent_sched_id) values
('Schedules',null, null), 
   ('Schedule 1',3,1), 
   ('Schedule 2',2,1), 
      ('Schedule 2-1',1,3), 
      ('Schedule 2-2',3,3), 
        ('Schedule 2-2-1',3,5), 
        ('Schedule 2-2-2',2,5), 
           ('Schedule 2-2-2-1',1,7);

-- TESTING

-- just call this stored procedure from your php

call schedule_hier(3);

sched_id    schedule_name   parent_sched_id parent_schedule_name    trainer_id  trainer_name    depth
========    =============   =============== ====================    ==========  ============    =====
3           Schedule 2          1         Schedules                2              trainer 2    0
4           Schedule 2-1        3         Schedule 2               1              trainer 1    1
5           Schedule 2-2        3         Schedule 2               3              trainer 3    1
6           Schedule 2-2-1      5         Schedule 2-2             3              trainer 3    2
7           Schedule 2-2-2      5         Schedule 2-2             2              trainer 2    2
8           Schedule 2-2-2-1    7         Schedule 2-2-2           1              trainer 1    3
于 2010-10-12T09:52:39.073 に答える