<?php
$dsn = '';
$user = '';
$password = '';

try {
    $dbh = new PDO($dsn, $user, $password);
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
}
?>



<?php
require 'mysqli_connect.php';
if(isset($_POST['submit']) && !empty($_POST['submit'])){

  $sth = $dbh->prepare('INSERT INTO test_table(comment) VALUES(?);');
  $comment = $_POST['comment'];
  $sth->execute(Array($comment));
}
?>

<form action = "<?php echo htmlspecialchars($_SERVER['PHP_SELF']);?>" method = "post">
      <p>Comment</p>
      <textarea name= "comment" rows="6" cols="50"></textarea><br />
      <input type="submit" name= "submit" value="submit" id = "submit">
    </form>