[Mediawiki-l] Storing additional user data

[Nick Bell]

I'd like to store an additional item of data ("grade") for each user, 
and set things up so only administrators can change the item, and admins 
can view a table showing every user's grade.

What do you think the easiest way of going about this is? I have written 
sites using PHP and MySQL before, but have never tinkered with MediaWiki!

Many thanks for your help

Nick