PHP Form with process on same page?

Question

I've created a form on my page and from the tutorials im following it says I have to have a second page with all the php processing in, is it not possible to keep the php on the same page and when the user hits submit the form is sent?

Why isnt this working on my process page? It doesnt echo anything :S

<?php 
$kop = mysql_real_escape_string($_POST['severity']);
$loc = mysql_real_escape_string($_POST['location']};
$summary = mysql_real_escape_string($_POST['summary']);
$name = mysql_real_escape_string($_POST['name']);
$email = mysql_real_escape_string($_POST['email']);

echo $kop;
echo $loc; 
echo $summary; 
echo $name; 
echo $email;
?>

Answer 1

You can check in the same file if the submit button is pressed. (http://pastebin.com/8FC1fFaf)

if (isset($_POST['submit'])) 
{ 
    // Process Form
}
else
{
    // Show Form
}

Regarding form checking, you can save the user input, and if one of their data is unvalid you can echo the old data back and show the form again.

edit: As PeeHaa stated, you need to leave the action blank though ;)