function get_array_needed() {
    $servername = "localhost";
    $username = "algolhos_unisitc";
    $password = "Un1s1t_commerce";
    $dbname = "algolhos_unisitc";

    // Create connection
    $conn = new mysqli($servername, $username, $password, $dbname);
    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    }

    $sql = "SELECT codice_target FROM customer";
    $result = $conn->query($sql);
    $rtoclass = array();

    if ($result->num_rows > 0) {
        // output data of each row
        while($row = $result->fetch_assoc()) {
            echo "id: " . $row["id_customer"]. " - Codice target: " . $row["codice_target"]."<br>";
            $rtoclass[] = $row;
        }
    } else {
        echo "0 results";
    }

    $conn->close();
    return $rtoclass;
}
    $obj->set_arr_needed( get_array_needed() ); // change $obj with the instance name writeToFile() is using...