if (isset($_POST['login']) && !empty($_POST["login"])) {
        $login = $_POST['login'];
    } else {
        $alert = "Pas de login entrer";
        echo $alert;
        return false;
    }
    if (isset($_POST["pass"]) && !empty($_POST["pass"])) {
        $pass = $_POST['pass'];
    } else {
        $alert = "Pas de pass entrer";
        echo $alert;
        return false;
    }
    $connexion_admin = new TraitementBdd();
    $verif = $connexion_admin->connexionAdmin($login, $pass);
    if ($verif != false) {
        $_SESSION['login'] = $login;
        $_SESSION['id'] = 1;
    } else {
        $alert = "Mauvais login ou mot de passe";
        echo $alert;
        return false;
    }
}
if (isset($_POST["valid_etude"])) {
    if (isset($_POST["date_debut_etude"]) && !empty($_POST['date_debut_etude'])) {
        $date_debut = $_POST['date_debut_etude'];
    } else {
        $date_debut = "non défini";
    }