Mysql dies with invalid user name or pass

[jack7076]

Hello I've written some code that dies when the msql lookup occurs and crashes when an invalid username or password is entered I want the code to continue and go to my invalid page. anyway here is the code:

echo "Before Query <br>";
	$query = mysql_query("SELECT *  FROM user where userName = '$_POST[user]' AND pass = '$pass'") or die(mysql_error());
	echo "row";
	$row = mysql_fetch_array($query) or die(mysql_error());
	echo "Before Login. <br>";
	if(!empty($row['userName']) AND !empty($row['pass']))
	{
		if($_POST['user'] = $row['userName'] AND $pass = $row['pass']){
		$_SESSION['ID'] = $row['ID'];
		$_SESSION['user'] = $row['userName'];
		$_SESSION['rank'] = $row['rank'];
		header("Location: Index.php");

	}
	else{
		header("Location: INVALID.php?ref=login");
	}
}
else
	{
		header("Location: INVALID.php?ref=login");
	}

[Jacques1]

Erase the code from your disk, forget what you think you know about PHP, start from scratch

• The Codeacademy PHP course (learning the basics of PHP)
• Exploits of a Mom (why security matters)
• (The only proper) PDO tutorial (how to communicate with a MySQL database in the 21st century)
• The PHP manual (lots of useful information and warnings)

[Jacques1]

... and I just realized this is a live site for a company.