Pros and Cons of a database driven website?

I'm looking at creating a large website that will involve displaying numerous arts and crafts tutorials, image gallery, forum and so forth.

However, initial plans indicate that things are going to get very messy very quickly, so I am playing with the idea of driving the entire site from a series of SQL databases.

How difficult is this going to be and are there any major drawbacks? I'm reasonably fluent in PHP/SQL so I don't think it's going to be a problem from the technical side of things, but what about the likes of SEO? Am I going to lose out on a lot of bot traffic going down this route?

Any thought and tips would be much appreciated.

Search engines only see the presented page. They have no idea whether that page is static or was built from content in a database.

In fact, if the page being built from a database also means it is changing often, the search engines will pick up on this and come back more frequently to see what has changed.