I have a structural question. I'm setting up a project management app. I need someway to give access to specific projects to specific users. Should I just create a row for each user for each new project and then just set 0 or 1 if I decide to give a particular user access? Originally I was only going to create a row in the access table for people who had access. The only problem with that is, when I try and delete users, or update status I'm having to do crazy checking to see if they're already exist.

What's the best way to do this?