Probably the easiest way to record the upload info like this would be to ensure that the user is logged in when uploading. You can then just record whatever user identifier you have stored in the session in your uploads table.
This way you can have a single table for uploads and another for users. In the upload table you will need to make sure you have a column for the userID. Then when you perform your insert into the upload table to record the details of the file you will also record the userID so you can search based on the user if you would like.
This relies on having the login in place and making sure that you are storing the userID in a session variable when the user logs in. This functionality is built into Security Assist in the Authenticate user server behavior.