Develop app

I want to use qr codes to access a membership site, so I need each individual code to be different and once a user scans a qr code it takes him to his membership site, because it recognizes his unique identifier, it then asks for a password as additional security. Once into the site the user should be able to add information to a database which is related to that specific qr code. If the user has additional qr codes with his unique identifier, he can also add information to these as long as it occurs with a few minutes and the system has not timed out. If the user comes back later and scans the initial qr code then it should bring up the entered information once verification has occurred and similarly each individual code added.