Hi! I'm designing a database for an MVC app that will eventually use Microsoft Accounts (in my AD) for login control. I haven't quite learned that part yet, but only need to get the database set up right now. The idea is that verified users can subscribe to chosen underlying data, so I have a simple Subscriptions table with SubscriptionID, a foreign key to underlying data structures, and a user field so the correct data can be shown. My problem (right now) is how to format that user field based on what AAD will need/want. Should the user field be GUID, or a varchar, or email? I'm sure there's a standard here that I just haven't found yet.
TIA
Re
Dennis