Kode verifikasi tidak merespon query sql server

halo semua senior, saya mencoba membuat form login dengan sql server dan ketika login tidak dapat membaca isi dari database dan menganggap login tsb selalu gagal. berikut adalah kode verifikasi loginnya :

<?php
session_start();
extract($_POST);
include 'konfig.php';
$query = "SELECT * FROM dbo.users WHERE user_fullname='$user_fullname' AND user_password='$user_password'";
$result = mssql_query($query);
if (mssql_num_rows($result)) {
    while ($row = mssql_fetch_array($result)){
      $_SESSION['user_id'] = $row['user_id'];
        $_SESSION['user_fullname'] = $row['user_fullname'];
        $_SESSION['user_password'] = $row['user_password'];
        $_SESSION['user_email'] = $row['user_email'];
        $_SESSION['user_status'] = $row['user_status'];
        $_SESSION['hak akses'] = $row['hak akses'];
}
if ($row['user_id'] == "1") {
    header("location:dokter.php?view=tampil_pasien_dokter");
} elseif ($row['user_id'] == "2") {
    header("location:front-office.php?view=tampil_pasien");
} elseif ($row['user_id'] == "3") {
    header("location:departemen.php?view=tampil_pasien");
}  elseif ($row['user_id'] == "4") {
        header("location:admin-kamar.php?view=tampil_kamar");
} else {
    echo '<script>href.location</script>';
    session_destroy();
}

}else{
echo "<script>
location.href='login2.php?error=salah';
</script>";
}
?>