How to automatically maintain a table of users that have been authenticated by IIS 7.0 using Windows Authentication

Question

I want to build and maintain a table of users. All users that access the ASP.NET MVC site are authenticated via Windows Authentication so they're bound to have a unique username. I'm grabbing the user name from:

System.Web.HttpContext.Current.User.Identity.Name

I feel like I could go two ways with this.

1. Anytime the user table or any tables that references the user table are accessed, I could add the user if it doesn't exist. I'm worried this might be very error prone if user's existance isn't checked.
2. Anytime the user visits any page on the site, check if that user exists in the db and if they don't exist, add the user. This may have a lot of overhead as it'll be checked every page change.

I'd like to hear which of these is the better solution and also how to implement them.

Answer 1

I think a better way would be something similar to the option two.
Anytime a user visits a page, check a session variable to see if that user was checked against the DB. If the session variable is not there, check if that user exists in the DB, add the user to your table if necessary, then set the session variable.
That way you don't have to hit the DB on every request.