How To Get Last Item Of An Array?

Hello Everyone, I have an multi-dimensional array called $cat_data, which is info extracted from a MySQL DB. I want to retrieve the very last item of that array. How would I do that? I know the first item can be retrieved by simply asking for $cat_data[0][0], which contains an id number. But I can't figure out how to get the last item in that same array -- $cat_data[x][0] where x is the last item in the array. P.S. - I read the section on Arrays at php.net, but unfortunately I didn't find my answer there. I also checked my PHP books, no mention of my problems there either.