SAS code help for monthly analysis

[adhi2823]

Thanks Paige for your code.

Reeza: What do you want me to explain? I apologize, being an international student, could not meet your standards in explaining things. However, let me try my best.

I have my data under two separate columns:

Column 1 (Month)               Column 2 (Customer ID)
201007                                   x1...xn

.                                               x1...xn                                          

.

.

.

.

.

201310                                   x1....xn

I want my result in following format:

Column 1 (Month)               Column 2 (New ID)               Column 3 (ID that exited)

New ID Definition: ID that never appear in last 12 months but appear in current month.

Exit ID Definition: ID that appeared 12 months before but never appeared for next 12 months (including current month).

I hope I explained my problem. If you think I am still unable to explain things, please let me know and I am happy to try as much as I can. Thanks a lot for your help.