gagal update?

<?php
$koneksi = mysqli_connect("localhost", "root", "", "posijb");
$noppb = $_POST['noppb'];
$tgl = $_POST['tgl'];
$jenis = $_POST['jenis'];
$keperluan = $_POST['keperluan'];
$ppb_id = $_POST['ppb_id'];

if (isset($_POST["deskripsi"]))
{
    $hoby = $_POST["deskripsi"];
    reset($hoby);
    $koneksi = mysqli_connect("localhost", "root", "", "posijb");
    foreach ($hoby as $key => $val)
    {
        $ppb_id = $_POST["ppb_id"][$key];
        $deskripsi = $_POST["deskripsi"][$key];
        $qty = $_POST["qty"][$key];
        $satuan = $_POST["satuan"][$key];
        $harga = $_POST["harga"][$key];
        $bayar = $_POST["bayar"][$key];
        $pembayaran = $_POST["pembayaran"][$key];
        $supplier_id = $_POST["supplier_id"][$key];
        $rekening = $_POST["rekening"][$key];

        if (mysqli_connect_errno())
        {
            echo "Failed to connect to MySQL: " . mysqli_connect_error();
            exit();
        }
        $sql_hoby = "replace into desppb(deskripsi, qty, satuan, harga, bayar, pembayaran, supplier_id, rekening)                                    VALUES('$deskripsi','$qty','$satuan','$harga','$bayar','$pembayaran','$supplier_id','$rekening') WHERE ppb_id=$ppb_id";
        $hasil_hoby = mysqli_query($koneksi, $sql_hoby);

    }
}

$sql = "replace into ppb(noppb,tgl,jenis,keperluan)
                      VALUES('$noppb','$tgl','$jenis','$keperluan')";
//$hasil = mysqli_query($koneksi, $sql);
$hasil_hoby = mysqli_query($koneksi, $sql);
//$ppb_id = mysqli_insert_id($koneksi);
//insert yg balikin id bukan update
if ($hasil_hoby)
{
    proses_hoby($ppb_id);
    redirect('ppb');
}
else
{
    echo "Data Gagal diinput";
}

?>