Yes, it's possible. Wordpress's PHP syntax differs a bit from standard PHP which may make the task more difficult, however it is possible.
If you want to add information into MYSQL via the Wordpress interface, you'll need to either locate a Wordpress template or find a Wordpress PHP page with little information that can easily be edited and add the form and query information.
Due to Wordpress' unique syntax, you're better off creating a separate PHP page and including it via Wordpress or linking to it.