What is the difference in the codes?(security)

[eluser]mdvaldosta[/eluser]
I suggest using the third code. It's cleaner, and does everything you need using the tools CI provides.

The second code, however, doesn't protect from XSS though as far as I know. Active record escapes data, but doesn't prevent xss. You need to do that with your post data, either through $this->input->post('post_data', TRUE) or in your config sitewide.