Please Kind to Help Me with Undefined Index

[gapracoolz]

i'm newbie in php...i have project build application with php and mysql.

this is my problem :

1. $op=$_GET['op']; (Undefined index)

2. <?php

// setting nama folder tempat upload
$uploaddir = 'data/';

// Undefined index
$fileName = $_FILES['userfile']['name'];

// Undefined index
$tmpName = $_FILES['userfile']['tmp_name'];

// Undefined index
$fileSize = $_FILES['userfile']['size'];

// Undefined index
$fileType = $_FILES['userfile']['type'];

// koneksi ke mysql
mysql_connect('localhost','root','hagapurnama');
mysql_select_db('perpustakaanarsip');

// menyimpan properti atau informasi file ke tabel upload dalam db
// dengan terlebih dahulu mengecek ada tidaknya nama file dalam tabel

$query = "SELECT count(*) as jum FROM upload WHERE name = '$fileName'";
$hasil = mysql_query($query);
$data = mysql_fetch_array($hasil);

if ($data['jum'] > 0)
{
$query = "UPDATE upload SET size = '$fileSize' WHERE name = '$fileName'";
}
else $query = "INSERT INTO upload (name, size, type) VALUES ('$fileName', '$fileSize', '$fileType')";

mysql_query($query);

// menggabungkan nama folder dan nama file
$uploadfile = $uploaddir . $fileName;

// proses upload file ke folder 'data'
if (move_uploaded_file($_FILES['userfile']['tmp_name'], $uploadfile)) {
?><script language="JavaScript">alert('Penambahan Ebook Berhasil !!');
document.location='edokumen.php'</script><?
} else {
?><script language="JavaScript">alert('GAGAL Menambah Koleksi Ebook !!');
document.location='edokumen.php'</script><?
}

?>

please kind to help me solve that problem

regards

[sneakyimp]

an 'undefined index' error happens when you refer to an array element which has not yet been defined and your PHP installation is configured to report errors of type E_NOTICE:

$some_variable = $my_array['not-yet-defined-index']; // will throw E_NOTICE 'undefined index' error

You can avoid this problem by checking to see if it's set first:

if (is_array($my_array) && isset($my_array['not-yet-defined-index'])) {
  $some_variable = $my_array['not-yet-defined-index'];
}

Another option (which is sometimes frowned upon) is to alter the error reporting settings in PHP so that this type of error is ignored. Look at error_reporting in your PHP.ini file.