addColumn('advertisements', 'html', 'text', ['null' => true]);
$this->changeColumn('advertisements', 'image_url', 'string', ['null' => true]);
$this->changeColumn('advertisements', 'referral_url', 'string', ['null' => true]);
$this->changeColumn('advertisements', 'width', 'integer', ['null' => true]);
$this->changeColumn('advertisements', 'height', 'integer', ['null' => true]);
}
}