Ошибка Invalid datetime format: 1366 Incorrect integer value: '' for column `main`.`new_comment`.`film_id` at row

У меня появилась ошибка:

Fatal error: Uncaught PDOException: SQLSTATE[22007]:Invalid datetime format: 1366 Incorrect integer value: '' for column main.new_comment.film_id at row 1 in C:\OSPanel\domains\localhost\includes\connection.php:159 Stack trace: #0 C:\OSPanel\domains\localhost\includes\connection.php(159): PDOStatement->execute(Array) #1 C:\OSPanel\domains\localhost\includes\addcomment.php(6): DB->addComment() #2 {main} thrown in C:\OSPanel\domains\localhost\includes\connection.php on line 159

Код:

public function addComment () {
    global $film_name;
    $stmt = $this->pdo->prepare('SELECT film_id FROM new_film WHERE film_name = ?');
    $stmt->execute([$film_name]);
    $film_id = $stmt->fetchColumn();
    $user_name = $_POST['username'];
    $comment = $_POST['comment'];
    $stmt = $this->pdo->prepare('INSERT INTO new_comment (author, text, pubgdate, film_id) VALUES (?, ?, ?, ?)');
    $stmt->execute([$user_name, $comment, date('Y-m-d H:i:s'), $film_id]);
  }

Что делать?