Chat bouton envoyer

<?php
mysql_connect('localhost', 'root','');
mysql_select_db('nicolas');
?>
<h1>Chat</h1>
<hr/>
<?php
$data1 = mysql_query('SELECT * FROM chat ORDER BY id DESC LIMIT 0,30');
while($donnees = mysql_fetch_array($data1)) {
echo '#'.$donnees['id']. ' par '.htmlspecialchars(stripslashes($donnees['pseudo'])) .' :<br>';
echo htmlspecialchars(stripslashes($donnees['message'])).'<br><br>';
}
?>
<hr/>
<?php
if(isset($_POST['pseudo']) AND isset($_POST['message'])) {
$pseudo = mysql_escape_string($_POST['pseudo']);
$message = mysql_escape_string($_POST['message']);
$nb_caracteres_message = strlen($message);

if($nb_caracteres_message < 500) {

mysql_query('INSERT INTO chat VALUES("","'.$pseudo.'", "'.$message.'")');
header('Location: chat.php');
}
else
{
echo 'Message trop long !';
}

{
?>
<form action="" method="post">
Pseudo : <input type="text" name="pseudo" /><br>
Message : <textarea name="message"></textarea><br>
<imput type="submit" value="Envoyer" />
</form>