automatically change number of bars in bar chart

Hi newsgroup,

is there a way in excel 2003 to automatically adjust the number of
bars that are displayed in a bar chart? (and in other charts as well?)

I've got a table with categories that adjusts automatically depending
on inputs, i.e. there can be 5 categories, 6, 10 or whatever. now if I
link the data ranges to this table then I get bars for each of the
rows in this table, even if there's no data (or "") in them. This
means that all the charts look awful.

can this be done automatically?

and a more advanced one:

i've got XY charts where I draw boxes for each of the categories, and
again the chart doesn't take into account empty categories.

finally: if the previous is possible, is there a way to adjust the
displayed legend automatically? again, it shows a category marker for
each row, even for the ones which are empty.

Many thanks for your help,

Best greets,

Chris