Any of those could be used, and your choice will not make much difference if you only ever have one access at a time. The choice starts to become more important if you have multiple simultaneous access and you are recording whether users are logged in or not.
For all of the possibilities you list above, you need to be careful of security. The temptation is to store the username and password in plain text. The security of that is gone as soon as anyone can get a copy of the database to examine. You need to encrypt the passwords somehow.
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