Условие на проверку полей

form name="comment" action="phpscript/comments.php" method="post">
  <p>
    <input class="inp" type="hidden" name="name" value="<?php echo $_SESSION['session_username'];?>" />
  </p>
   <p>
    <input class="inp"  type="hidden" name="datetime" value="<?php echo date("Y-m-d H:i:s"); ?>" />
  </p>
  <p>
    <label>Комментарий:</label>
    <br />
    <textarea rows="4" cols="43" name="text_comment" cols="26" rows="3"></textarea>
  </p>
  <p>
    <input  type="hidden" name="id_news" value="<?= $_GET['id']?>" />
    <input id="bt" type="submit" value="Отправить" />
  </p>
</form>

<?php
  $mysqli = new mysqli("localhost", "Xelinel32", "ArT1999eM", "colevents");
  $name = $_POST["name"];
  $date = $_POST["datetime"];
  $id_news = $_POST["id_news"];
  $text_comment = $_POST["text_comment"];
  $name = htmlspecialchars($name);
  $text_comment = htmlspecialchars($text_comment);
  $mysqli->query("INSERT INTO `comments` (`author`, `id_news`, `text`,`datetime`) VALUES ('$name', '$id_news', '$text_comment','$date')");
  header("Location: ".$_SERVER["HTTP_REFERER"]);
?>

if ( strlen($_POST["text_comment"]) > 0 ) {} else { echo 'error';}

<?php
  $mysqli = new mysqli("localhost", "Xelinel32", "ArT1999eM", "colevents");
  $name = $_POST["name"];
  $date = $_POST["datetime"];
  $id_news = $_POST["id_news"];
  $text_comment = $_POST["text_comment"];
  $name = htmlspecialchars($name);
  $text_comment = htmlspecialchars($text_comment);
  if ( strlen($_POST["text_comment"]) > 0 ) {
  $mysqli->query("INSERT INTO `comments` (`author`, `id_news`, `text`,`datetime`) VALUES ('$name', '$id_news', '$text_comment','$date')");
  header("Location: ".$_SERVER["HTTP_REFERER"]);
  } else { echo 'error';
}
 
?>