When users log in at my web album, I want to show how many new pictures there are in each part of the album. In the user table I've got a column for the last login date, and for each picture I record when it was added to the database.

In it's most simple form, all I've got to do is to compare the last login date with the added dates in the picture table.

But what if I want a more advanced version, where I not only compare dates, but checks if the user actually has viewed the picture or not. How is this most easily done? With a new table linking user id's to picture id's, where I record which pictures the user has viewed? Or is there some other way?