Nope, no looping in Crystal 7. doesn't 'arrive' until 8 or 8.5
I think, you will have to do the looping yourself....Lots of if then lines. And that might not be enough.
The easiest way, in this situation, is to get the data via a stored proc, you can do the looping in the stored proc and return the value that you need in a column. My reports tend to have lots of columns, since I believe in letting each type of software do what it is best at...SQL for the data and Crystal for the display.
I know, this is not always possible.
HTH