Try using the "Split" function. Your formula (I'll call it {@Values} will look something like this:
StringVar Array values = split({table.field}, ',')
You can then use the values array in other formulas to do your individual comparisons. You just need to remember to declare it in each formula where it's used so that the formula knows about it. This will look like this:
StringVar values;
<do your comparison>
If you haven't used variables in Crystal before, they can be a little tricky. So, if you let me know specifically what your trying to do with your comparisons, I might be able to help with the exact syntax.
-Dell