Two important clocks of code to create new messages and polls.

Post.php

// Sources/Post.php@1828
// This bit creates a new poll in the database


if (isset($_REQUEST['poll']))
	{
		// Create the poll.
		$smcFunc['db_insert']('',
			'{db_prefix}polls',
			array(
				'question' => 'string-255', 'hide_results' => 'int', 'max_votes' => 'int', 'expire_time' => 'int', 'id_member' => 'int',
				'poster_name' => 'string-255', 'change_vote' => 'int', 'guest_vote' => 'int'
			),
			array(
				$_POST['question'], $_POST['poll_hide'], $_POST['poll_max_votes'], (empty($_POST['poll_expire']) ? 0 : time() + $_POST['poll_expire'] * 3600 * 24), $user_info['id'],
				$_POST['guestname'], $_POST['poll_change_vote'], $_POST['poll_guest_vote'],
			),
			array('id_poll')
		);
		$id_poll = $smcFunc['db_insert_id']('{db_prefix}polls', 'id_poll');

		// Create each answer choice.
		$i = 0;
		$pollOptions = array();
		foreach ($_POST['options'] as $option)
		{
			$pollOptions[] = array($id_poll, $i, $option);
			$i++;
		}

		$smcFunc['db_insert']('insert',
			'{db_prefix}poll_choices',
			array('id_poll' => 'int', 'id_choice' => 'int', 'label' => 'string-255'),
			$pollOptions,
			array('id_poll', 'id_choice')
		);
	}

Subs-Post.php

// Sources/Subs-Post.php@1804
// This creates a new post. It uses their special format $smcFunc['db_insert'](...)

// Insert the post.
	$smcFunc['db_insert']('',
		'{db_prefix}messages',
		array(
			'id_board' => 'int', 'id_topic' => 'int', 'id_member' => 'int', 'subject' => 'string-255', 'body' => (!empty($modSettings['max_messageLength']) && $modSettings['max_messageLength'] > 65534 ? 'string-' . $modSettings['max_messageLength'] : 'string-65534'),
			'poster_name' => 'string-255', 'poster_email' => 'string-255', 'poster_time' => 'int', 'poster_ip' => 'string-255',
			'smileys_enabled' => 'int', 'modified_name' => 'string', 'icon' => 'string-16', 'approved' => 'int',
		),
		array(
			$topicOptions['board'], $topicOptions['id'], $posterOptions['id'], $msgOptions['subject'], $msgOptions['body'],
			$posterOptions['name'], $posterOptions['email'], time(), $posterOptions['ip'],
			$msgOptions['smileys_enabled'] ? 1 : 0, '', $msgOptions['icon'], $msgOptions['approved'],
		),
		array('id_msg')
	);
	$msgOptions['id'] = $smcFunc['db_insert_id']('{db_prefix}messages', 'id_msg');

	// Something went wrong creating the message...
	if (empty($msgOptions['id']))
		return false;