tranquillement ça avance et je pense comprendre...
j'ai donc 2 table, une qui enregistre les moyennes pour l'affichage et l'autre qui enregistre 1 votes par champs avec toutes les infos utiles pour n'autoriser qu'un votes par personne.

quand on enregistre un nouvel individu, aucun vote n’existe donc a l’affichage de sa page, une requete crée un premier champ dans chaque table pour permettre l’affichage...

voila le code:

                try
                {
                    //connexion
                    $dbh = new PDO('mysql:host='.$PARAM_hote.';dbname='.$PARAM_nom_bd, $PARAM_utilisateur, $PARAM_mot_passe);
                    $dbh->setAttribute (PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

                    // protection de la chaine chien pour une requete
                    $this->chien = $dbh->quote($vote_chien);

                    // js cherche si le chien a le vote avec l'ip admin
                    $vote_chien_check = $dbh->query("SELECT id FROM vote WHERE ip_user='admin' AND id_chien=$this->chien LIMIT 0, 1");
                                   
                    // si $vote_chien_check est vide
                    if(empty($vote_chien_check))
                    {
                        // je crée un premier vote dans la table vote
                        $dbh->exec("INSERT INTO vote (id_question, id, ip_user, id_chien, note) 
                                     VALUES ('1', '1', 'admin', $this->chien, '')");
                        // je crée un premier vote dans la table moyenne_votes
                        $dbh->exec("INSERT INTO moyenne_votes (id_chien, id_question, nb_votes, moyenne) 
                                                       VALUES ($this->chien, '1', '', '')");                        
                        
                    } 
                    
                    // ???                    
                    else 
                    {
                        $this->average = $vote_chien_check->fetchColumn(1);
                    }

                    // ???
                    $this->votes = ($dbh->query("SELECT nb_votes FROM moyenne_votes WHERE id_chien=$this->chien")->fetchColumn()-1);
		}catch( PDOException $exception ){
				die($exception->getMessage());
		}
		$dbh = NULL;		
	}

mon soucis la c'est la vérification de $vote_chien_check, si je met un "if(!empty($vote_chien_check))" le système semble marcher mais chaque fois que j'actualise la page, les champs sont créer de nouveaux et les votes augmentes et si je met "if(empty($vote_chien_check))" ce qui me parait plus correct la rien ne marche ???

bon, j'ai réussi quelques modifs mais ce create table me pose problème, je vous fait vois le code d'origine:

<?php
class rating{

	public $average = 0;
	public $votes;
	public $status;
	public $table;
	private $path;
	
	function __construct($table){
		try{
			$pathinfo = pathinfo(__FILE__);
			$this->path = realpath($pathinfo['dirname']) . "/database/ratings.sqlite";
			$dbh = new PDO("sqlite:$this->path");
			$this->table = $dbh->quote($table);
			// check if table needs to be created
			$table_check = $dbh->query("SELECT * FROM $this->table WHERE id='1'");
			if(!$table_check){
				// create database table
				$dbh->query("CREATE TABLE $this->table (id INTEGER PRIMARY KEY, rating FLOAT(3,2), ip VARCHAR(15))");
				$dbh->query("INSERT INTO $this->table (rating, ip) VALUES (0, 'master')");				
			} else {
				$this->average = $table_check->fetchColumn(1);
			}
			$this->votes = ($dbh->query("SELECT COUNT(*) FROM $this->table")->fetchColumn()-1);
		}catch( PDOException $exception ){
				die($exception->getMessage());
		}
		$dbh = NULL;		
	}

	function set_score($score, $ip){
		try{
			$dbh = new PDO("sqlite:$this->path");
			$voted = $dbh->query("SELECT id FROM $this->table WHERE ip='$ip'");
			if(sizeof($voted->fetchAll())==0){
				
				$dbh->query("INSERT INTO $this->table (rating, ip) VALUES ($score, '$ip')");
				$this->votes++;
				
				//cache average in the master row
				$statement = $dbh->query("SELECT rating FROM $this->table");
				$total = $quantity = 0;
				$row = $statement->fetch(); //skip the master row
				while($row = $statement->fetch()){
					$total = $total + $row[0];
					$quantity++;
				}
				$this->average = round((($total*20)/$quantity),0);
				$statement = $dbh->query("UPDATE $this->table SET rating = $this->average WHERE id=1");
				$this->status = '(thanks!)';
			} else {
				$this->status = '(already scored)';
			}
			
		}catch( PDOException $exception ){
				die($exception->getMessage());
		}
		$dbh = NULL;
	}
}

function rating_form($table){
	$ip = $_SERVER["REMOTE_ADDR"];
	if(!isset($table) && isset($_GET['table'])){
		$table = $_GET['table'];
	}
	$rating = new rating($table);
	$status = "<div class='score'>
				<a class='score1' href='?score=1&table=$table&user=$ip'>1</a>
				<a class='score2' href='?score=2&table=$table&user=$ip'>2</a>
				<a class='score3' href='?score=3&table=$table&user=$ip'>3</a>
				<a class='score4' href='?score=4&table=$table&user=$ip'>4</a>
				<a class='score5' href='?score=5&table=$table&user=$ip'>5</a>
			</div>
	";
	if(isset($_GET['score'])){
		$score = $_GET['score'];
		if(is_numeric($score) && $score <=5 && $score >=1 && ($table==$_GET['table']) && isset($_GET["user"]) && $ip==$_GET["user"]){
			$rating->set_score($score, $ip);
			$status = $rating->status;
		}
	}
	if(!isset($_GET['update'])){ echo "<div class='rating_wrapper'>"; }
	?>
	<?php print_r($rating);?>
	
	<div class="sp_rating">
		<div class="rating">Rating:</div>
		<div class="base"><div class="average" style="width:<?php echo $rating->average; ?>%"><?php echo $rating->average; ?></div></div>
		<div class="votes"><?php echo $rating->votes; ?> votes</div>
		<div class="status">
			<?php echo $status; ?>
		</div>
	</div>
	<?php
	if(!isset($_GET['update'])){ echo "</div>"; }
}

if(isset($_GET['update'])&&isset($_GET['table'])){
	rating_form($_GET['table']);
}
?>

si je fait un <?php print_r($rating);?>, j'obtiens:
rating Object ( [average] => 80.0 [votes] => 1 [status] => [table] => '1' [path:rating:private] => C:\wamp\www\vote\rating/database/ratings.sqlite )
rating Object ( [average] => 0.0 [votes] => 0 [status] => [table] => '2' [path:rating:private] => C:\wamp\www\vote\rating/database/ratings.sqlite )
rating Object ( [average] => 100.0 [votes] => 1 [status] => [table] => '3' [path:rating:private] => C:\wamp\www\vote\rating/database/ratings.sqlite )


et le code modifié pour mon systeme:

<?php
class rating{

    public $average = 0;
    public $votes;
    public $status;
    public $table;

function __construct($table)
{
    $hote='localhost';           
    $nom_bd='aaaa';
    $utilisateur='root';             
    $mot_passe='';        

    try
    {   
        //connexion
        $dbh = new PDO('mysql:host='.$hote.';dbname='.$nom_bd, $utilisateur, $mot_passe);
        $dbh -> setAttribute (PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $this->table = $dbh->quote($table);	

        // recherche si un champ pour ce chien et cette question existe
        $table_check = $dbh->query("SELECT id_chien FROM vote WHERE id_chien=$this->table AND id_question='1'");
        $dnn = $table_check->fetch();	

        // test si $dnn contient un id_chien
        if(empty($dnn)) 
        {
            // je crée un premier vote dans la table vote
            $dbh->exec("INSERT INTO vote (id_question, id, ip_user, id_chien, note) VALUES ('1', '1', 'systeme', $this->table, '')");				
            // je crée un premier vote dans la table moyenne_votes pour enregistrer les moyennes
            $dbh->exec("INSERT INTO moyenne_votes (id_chien, id_question, nb_votes, moyenne) VALUES ($this->table, '1', '', '')"); 
        } 
        else 
        {
            $this->average = $table_check->fetchColumn(1);
        }
        
        // calcul du nombre de votes
        $this->votes = ($dbh->query("SELECT COUNT(*) FROM vote WHERE id_chien=$this->table")->fetchColumn()-1);

    }
        catch( PDOException $exception )
    {
        die($exception->getMessage());
    }
    $dbh = NULL;		
}





function set_score($score, $ip)
{
    try
    {
        //connexion
        $dbh = new PDO('mysql:host='.$hote.';dbname='.$nom_bd, $utilisateur, $mot_passe);
        $dbh -> setAttribute (PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        
        // recherche id vote avec (id-chien + id_question + ip_user)
	$voted = $dbh->query("SELECT id FROM votes WHERE id_chien=$this->table AND ip='$ip'");
	$dnn_2 = $voted->fetch();	
        
        // si cette combinaison n'existe pas
        if(empty($dnn)) {
				
	// j'insert le vote
        $dbh->exec("INSERT INTO vote (id_question, id, ip_user, rating, id_chien) VALUES ('1', '1', '.$ip.', $score, $this->table)");
	$this->votes++;
		
        // ???
	$statement = $dbh->query("SELECT rating FROM vote WHERE id_chien=$this->table");
	$total = $quantity = 0;
	$row = $statement->fetch();
	while($row = $statement->fetch())
        {
            $total = $total + $row[0];
            $quantity++;
	}
	$this->average = round((($total*20)/$quantity),0);
        $statement = $dbh->exec("UPDATE vote SET rating=$this->average WHERE id_chien=$this->table");
        $this->status = '(thanks!)';
	} 
        else 
        {
            $this->status = '(already scored)';
	}
			
	}catch( PDOException $exception ){
            die($exception->getMessage());
	}
	$dbh = NULL;
	}
   }

function rating_form($table){
	$ip = $_SERVER["REMOTE_ADDR"];
	if(!isset($table) && isset($_GET['table'])){
		$table = $_GET['table'];
	}
	$rating = new rating($table);
	$status = "<div class='score'>
				<a class='score1' href='?score=1&table=$table&user=$ip'>1</a>
				<a class='score2' href='?score=2&table=$table&user=$ip'>2</a>
				<a class='score3' href='?score=3&table=$table&user=$ip'>3</a>
				<a class='score4' href='?score=4&table=$table&user=$ip'>4</a>
				<a class='score5' href='?score=5&table=$table&user=$ip'>5</a>
			</div>
	";
	if(isset($_GET['score'])){
		$score = $_GET['score'];
		if(is_numeric($score) && $score <=5 && $score >=1 && ($table==$_GET['table']) && isset($_GET["user"]) && $ip==$_GET["user"]){
			$rating->set_score($score, $ip);
			$status = $rating->status;
		}
	}
	if(!isset($_GET['update'])){ echo "<div class='rating_wrapper'>"; }
	?>


	<div class="sp_rating">
		<div class="rating">Rating:</div>
		<div class="base"><div class="average" style="width:<?php echo $rating->average; ?>%"><?php echo $rating->average; ?></div></div>
		<div class="votes"><?php echo $rating->votes; ?> votes</div>
		<div class="status">
			<?php echo $status; ?>
		</div>
	</div>
	<?php
	if(!isset($_GET['update'])){ echo "</div>"; }
}

if(isset($_GET['update'])&&isset($_GET['table'])){
	rating_form($_GET['table']);
}

?>

et si je fait:<?php print_r($rating);?>, j'obtiens:

rating Object ( [average] => [votes] => 0 [status] => [table] => '1' )
rating Object ( [average] => [votes] => 0 [status] => [table] => '2' )
rating Object ( [average] => [votes] => 0 [status] => [table] => '3' )

j'arrive pas a m'en sortir, quelqu'un peut il m'aidé svp ?