Yes; in my table designs I will often use an AUTO_INCREMENT INT value as the PRIMARY KEY to link tables on. So each user has a `userID` field that is the most basic, simple method to refer to that user, regardless of how many columns and how much data is stored in them. Link it in the session data and the `logins` table if you are so inclined to add one. No need to store the username or any other data if you simply store the `userID`.

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