[Help]Can't get the data from Database

[eluser]iamleeloo[/eluser]
I copied and wrote some code yesterday. But the result was not satisfied.

I created 2 tables in a database named "test".
Table1: named "test" and there is 2 rows. "id" and "letters"
Data in table1: 3groups, (1,restaurant), (2,repas), (3,resto)
Table2: named "relation" and there is 3 rows. "relation_id" and "mot_1" and "mot_2"
Data in table2: 2groups, (1,restaurant,repas), (2,restaurant,resto)

[eluser]iamleeloo[/eluser]
Here are the codes:
words_model.php
<?php
class Words_model extends CI_Model {

public function __construct()
{
$this->load->database();
}

public function get_words($zimu)
{
$query = $this->db->query("SELECT * FROM test WHERE letters = '$zimu';");
return $query->result_array();
}

public function get_relation_mots($zimu)
{
$query = $this->db->query("SELECT mot_2 FROM relation WHERE mot_1 = '$zimu';");
return $query->result_array();
}
}

[eluser]iamleeloo[/eluser]
words_db.php
<?php
class Words_db extends CI_Controller {

public function __construct()
{
parent::__construct();
$this->load->model('words_model');
}

public function index()
{
$data['words'] = $this->words_model->get_words('restaurant'); //Get the value of "id" and "letters" of "restaurant" in table "test"
$data['title'] = 'Words';
$data['relation_mots'] = $this->words_model->get_relation_mots('restaurant'); //Get the values of "mot_2" of "mot_1=restaurant" in table "relation". They are"repas" and "resto".

$counter = 0;
foreach ($data['relation_mots'] as $relation_mots_item):
{
$data['relation_mots_id2'][$counter] = $this->words_model->get_words($relation_mots_item['mot_2']); //Get the value of "id" and "letters" of "repas" and "resto" in table "test"
$counter = $counter+1;
}
endforeach;

$data['counter'] = $counter;

$this->load->view('templates/header', $data);
$this->load->view('words_db/index', $data);
$this->load->view('templates/footer');
}
}

[eluser]iamleeloo[/eluser]
I don't know why I can't post full codes in index.php.

The key code are:
<?php

for ($relation_mots_id_counter=0; $relation_mots_id_counter<$counter; $relation_mots_id_counter++)
{
echo $relation_mots_id2[$relation_mots_id_counter]['id']; //Output the value of "id" of "repas" and "resto" in table "test"
}
?&gt;

But on the final page, these words are displayed:
"A PHP Error was encountered
Severity: Notice
Message: Undefined index: id
Filename: words_db/index.php
Line Number: 26"

What should I do?
Thanks.