Could you tell me what is wrong with this piece of code for my blog?

Question

If I remove this code, my page loads. But If I add this, I get a HTTP Error 500 from my web matrix.

<?php
try {    
  if(isset(['submit'])) {
    include('config.php');
    $subject = $_POST['subject'];
    $content = $_POST['editor1'];
    $date = $_POST['date'];
    $tags = $_POST['tags'];
    $author = $_POST['author'];
    $thumbnail = $_POST['thumbnail'];
    $sql = "INSERT INTO articles (Subject, Content, Date, Author, Tags, Thumbnail) VALUES ('$subject','$content','$date','$author','$tags', '$thumbnail')";
    $dbh->query($sql);   
  }
} catch(PDOException $e) {
   echo $e->getMessage();
}
?>

Answer 1

In the line

if (isset(['submit']))

there is a variable missing. You may want to use this line:

if(isset($_POST['submit']))

By the way your SQL code is open for blind SQL injections. You should parse the parameter or better still, use prepared statements.

$stmt = $dbh->prepare("INSERT INTO articles (Subject, Content, Date, Author, Tags, Thumbnail) VALUES (':subject',':content',':date',':author',':tags', ':thumbnail')");
$stmt->bindParam(':subject', $subject);
$stmt->bindParam(':content', $content);
// ...
$stmt->execute();

Answer 2

This is not a statement:

if (isset(['submit']))

it should be:

if (isset($_POST['submit']))

with all chance.

Anyway, you should bind parameters to the query, and not hardcode them into it.