Hi
Not sure what you are trying to do there...
You want to show the article's category title for the article instead of the articles actual title?
For these sort of things I would use select dynamic field or even the beforerender field.
Using the category field it is meant to show the category name and store the id, select dynamic can do the same and is more flexible / versatile ......
where are trying to do this ... front end , back end, list view, content view etc?