Yet another PHP/MySQL user management question on the site: PHPKode. It's for
an image editor, and so each user should have their own "space" i.e. user
directory (USERDIR) upon signing up, and anything under that directory should
be accessible to the relevant user only. Fairly simple step up but I can't
seem to find the right keywords to search for a tutorial.

The way I was thinking of implementing it is having a "USERDIR" column in the
MySQL db along side "USERID" and "PASSWORD" (md5 hashed) (although I
understand USERDIR is a redundant key if USERIDs are also unique - is this an
issue to be worried about? i.e. I could just assign the USERID as the
directory name instead of generating a unique random directory name). How do I
then "check" whether the user has the privileges to access their directory
(i.e. how do I code it to check the sessionID/cookie checking to stop another
user from going to mysite.com/USERID or mysite.com/USERDIR). I appreciate this
is really basic and repetitive for some of you but I can't seem to find the
relevant tutorials anywhere! Any help much appreciated.