How to use a ranbom generator ...advanced style???

[James54321]

Hi, I did quite a bad subject heading so I'll try to explain it better
here.

I have a website (it is indeed really bad right now, I know that, so
please don't remind me). For a very long time now I have wanted it to
display a random slogan of my site from all of the possible slogans
that are stored in my MySQL database. I have recently found out how
to count the rows of a MySQL table and so I have made a script that
will select an appropriate row (according to the list of rows 1-12 for
example). BUT the problem I am having is that if i have a row that
I've deleted then that row can still be selected, as I have no way
(that I know) as to reference which rows are not deleted ..to be able
to ONLY show the slogans and not just an empty row of nothingness.

Is this possible, and if so, how?

P.S.
You can see the page which outputs the relevant random number here:
http://flavouredcandy.com/page.php?id=2 (its just under the right
banner).

Thanks, James.