问使用php从数据库获取数据，但它只返回一个结果

EN

$statement3 = mysqli_prepare($con, "SELECT * FROM client_ble_gateway WHERE username = ?");

mysqli_stmt_bind_param($statement3, "s", $username);
mysqli_stmt_execute($statement3);
mysqli_stmt_store_result($statement3);
mysqli_stmt_bind_result($statement3, $ble_id, $client_id, $alias, $serial_number, $share_data, $latitude, $longitude,$username);


while(mysqli_stmt_fetch($statement3)){

    $res["ble_id"]=$ble_id;
    $res["alias"]=$alias;
    $res["serial_number"]=$serial_number;
}

$res=array($ble_id, $alias, $serial_number);
echo json_encode($res);