I'm designing a game where a character has many items and those items can be of many types. There is a character table, and twelve different tables of possible items broken down by type (such as weapons, armors, and various other item types).

I want to make a table to hold instances of these item types (basically a characters' items table) every row will have a foreign key from the characters' table to indicate which character has ownership of that item.

At first I figured I'd make foreign keys in the characters' items table -- one key for each of the twelve item tables. But since every item can be of only one "type," that would lead to eleven null fields in every row, and that seems wrong.

What would be the better approach? I've yet to build the database, so I can entertain other inventory ideas that don't use twelve item tables, but know this: the admin interface will allow a user to add/remove/modify items of each type as needed.

Also, I'd like to stick to the best normalization practice, so I'll ignore the inevitable "Who cares? Just do what works and use null-able fields."