Cast MySQL table to float array using PHP PDO

Question

I want to get a multidimentional php array from MySQL database where I want to cast a field to float.

I'm using PHP 5.3 and MySQL 5

and this is my code:

*** My PDO class:

class DB {
    private static $instance = NULL;
    public static function getInstance() {

        if (!self::$instance) {
            try {
                self::$instance = new PDO("mysql:host=" . SERVER . ";dbname=" . DtB, USR, PASS);
                self::$instance->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
                self::$instance->setAttribute(PDO::ATTR_EMULATE_PREPARES, 0);                    
                self::$instance->query("SET character_set_results = 'utf8', character_set_client = 'utf8', character_set_connection = 'utf8', character_set_database = 'utf8', character_set_server = 'utf8'");
            } catch (PDOException $e) {
                echo 'Échec lors de la connexion : ' . $e->getMessage();
            }
        }
        return self::$instance;
    }

    private function __clone() {
        /* interdiction de cloner l'instance */
    }
}

And I use it like this:

$datas1 = $db->query('
SELECT 
  r.nom AS nomReg, 
  COUNT(e.regions) AS nbr 
FROM regions r  
LEFT OUTER JOIN event e ON r.nom=e.regions
GROUP BY r.nom
')->fetchAll(PDO::FETCH_ASSOC);

and :

$dataTypes=$db->query("
SELECT tt.nomtype_tache AS name, 
    CAST(((COUNT(t.nomtype_tache) / (
                           SELECT count(t.idtype_tache) AS y
                           FROM type_tache tt 
                           LEFT OUTER JOIN tache t 
                           ON tt.idtype_tache = t.idtype_tache
                                 )
                 ) * 100) AS DECIMAL(5,1)) AS y 
FROM type_tache tt 
LEFT OUTER JOIN tache t ON tt.idtype_tache = t.idtype_tache 
GROUP BY name
")->fetchAll(PDO::FETCH_ASSOC);

and this the var_dump of these variables:

$datas1:

    array (size=4)
  0 => 
    array (size=2)
      'nomReg' => string 'ARIANA' (length=6)
      'nbr' => int 1
  1 => 
    array (size=2)
      'nomReg' => string 'BEJA' (length=4)
      'nbr' => int 0
  2 => 
    array (size=2)
      'nomReg' => string 'BEN AROUS' (length=9)
      'nbr' => int 1
  3 => 
    array (size=2)
      'nomReg' => string 'BIZERTE' (length=7)
      'nbr' => int 0

$dataTypes:

array (size=3)
  0 => 
    array (size=2)
      'name' => string 'type1' (length=5)
      'y' => string '0.0' (length=3)
  1 => 
    array (size=2)
      'name' => string 'type2' (length=5)
      'y' => string '0.0' (length=3)
  2 => 
    array (size=2)
      'name' => string 'type3' (length=5)
      'y' => string '13.3' (length=4)

I don't no what is the problem that don't make the 'y' field to be float???