Have your file structre like
ID
User_ID
File_Name

That way they can upload as many files as they need and they are linked. You could then either left join that table on users.id = files.User_ID or seperately query everything where the files user_id is equal to the users ID.

Also, dont store files in the database like that. It will slow everything down and will be in no way shape or form more efficient.

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