Working on a database with almost 40,000 contact records. Not all of these people will be logging, not nearly all of them in fact. However, many people will be logging in. Our database contains senesitive records for all of our clients, and the user logged in should only be able to view the records that apply to themselves. I want to use an email based login, so what is the best way to have them login and only be able to view records that are attached to their Contact pk without having to personally go in and create user accounts for every new and pre-existing client that will need access to our database?