SQL - Php - 2 Requêtes - Problème

SELECT `timestamp`, `sensor`, `value` FROM sensorparser WHERE `timestamp` > CURDATE() - INTERVAL 1 MONTH AND `sensor` = blabla 

SELECT `timestamp`, `sensor`, `value` FROM sensorparser WHERE `timestamp` > CURDATE() - INTERVAL 1 MONTH AND `sensor` = ' blabla'

<?php

class Database {

    private $host = "xxxxxx";
    private $username = "yyyyy";
    private $password = "yyyy";
    private $database = "yyyyyyyyyyyyyyyy";

    public $connexion;

	function __construct(){
		$this->getconnexion();
	}
	
    public function getconnexion() {
        $this->connexion = null;

        try {
            $this->connexion = new PDO("mysql:host=".$this->host.";dbname=".$this->database .'charset=utf8', $this->username, $this->password);
            // Activation des erreurs PDO
			 $this->connexion->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
			// mode de fetch par défaut : FETCH_ASSOC / FETCH_OBJ / FETCH_BOTH
			 $this->connexion->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
        } catch (PDOException $exception) {
            echo "Error: ".$exception->getMessage();
            die();
        }
        return $this->connexion;
    }

    public function closeconnexion() {
        $this->connexion = null;
    }
	
	
	/**
	Execution d'une requete preparee
	*/
	public function db_Exec($sql,$datas=NULL){
	
		//Execution de la requete
		try{
		  $requete = $this->connexion->prepare($sql) ;
		  $requete->execute($datas) ;
		}catch(Exception $e){
		  // en cas d'erreur :
		   echo " Erreur ! ".$e->getMessage();
		   echo " Les datas : " ;
		  print_r($datas);
		  exit;
		}
		return $requete;
	}
	
	/**
	 Requête SELECT
	 @sql string
	 @datas array
	 @return Array
	*/
	public function db_All($sql,$datas=NULL){
		$req = $this->db_Exec($sql,$datas);
		return $req->fetchAll();
	}

}


?>

<?php
 //Affichage des erreurs PHP
 error_reporting(E_ALL);
ini_set('display_errors', TRUE);
ini_set('display_startup_errors', TRUE);

//class de connexion à la bdd
require_once 'Database.php';
 
$oDb  = new Database();
//$con = $oDb->getConnection(); // plus besoin, c'est dans le construct..
 
$p = !empty($_GET['periode']) ? (int)$_GET['periode'] : 1;
$c = !empty($_GET['capteur']) ? $_GET['capteur'] : 'TC';

$periode = [1 => 'HOUR', 2 => 'DAY', 3 => 'WEEK', 4 => 'MONTH', 5 => 'YEAR'][$p] ?? 'HOUR';
 $caps = [ 'CO' => 'blabla', 'CO2' => 'blabla', 'LUX'=> 'blabla', 'BAT' => 'blabla', 'HALL' => 'blabla', 'LP' => 'blabla',
		  'PIR' => 'blabla', 'STR' => 'blabla', 'HUM' => 'blabla', 'PRES' => 'blabla', 'TC' => 'blabla'
		 ];
		 
$capteur = !empty($caps[$c]) ? $caps[$c] : 'TC';
 
$sql = <<<sql
SELECT `timestamp`, `sensor`, `value` 
  FROM sensorparser 
 WHERE `timestamp` > CURDATE() - INTERVAL 1 {$periode}
       AND `sensor` = :capteur 
sql;
$datas = array(':capteur'=>$capteur);

$res = $oDb->db_All($sql,$datas);

if(!empty($res)){
  $json = json_encode($res);
  echo strtr($json, ['filename' => 'fileName', 'folderdirectory' => 'folderDirectory', 'lastchange' => 'lastChange']);
}else{
  echo "No result !";
}

$datas = array(':capteur'=>$capteur);

$datas = array(':capteur'=>$c);