Difference between Dates

Hi ,

I am working on a report that has ID, Exam , Name and Date. Now there are cases where for ID , Exam , and Names we have multiple records (2 or more).

I need to show the records having 30 days or less difference. I need to calculate the difference in dates in loop. If the no of records are 2 , I take min and max dates and calculate the daysdifference. How to do for cases with more than 2 records.

Any suggestions?

Thanks.