URL of edit page like Stack Overflow edit page

I noted that on Stac开发者_开发百科k Overflow when editing a question or answer it opens the same URL with different ids. These ids are continually ids, for example:

1. http://stackoverflow.com/posts/1232345/edit
2. http://stackoverflow.com/posts/1232346/edit

1^st URL is to edit a question, but the 2^nd is to edit an answer.

How can I implement something like that? I thought there are two tables, one for questions and another for answers, so how can I put continually ids in two different tables? What is the idea behind that?

No, both questions and answers are in one table (on Stack Overflow) named Posts, with column PostType (1 (question) or 2 (answer))