/config/includes/bdd/prepare.php

<?php
/**
* Requête à la base de données.
*/

function prepare($statement, $values) {
    $database = new Database();
    $bdd = $database->BDD();
    $request = $bdd->prepare($statement);
    $request->execute($values);
    return $request;
}

function countDatabaseValue($key, $value) {
    $database = new Database();
    $bdd = $database->BDD();
    $request = $bdd->prepare("SELECT * FROM users WHERE $key = ?");
    echo $request;
    $request->execute(array($value));
    return $request->rowCount();
}
?>