identifying observations 12 month period

[G_I_Jeff]

I can't find an example using a DATA step with multiple SET statements.

I need to find previous 12 months observations based off a DATETIME value.

I'm pulling previous month easily by:

MONTH(DATEPART(DATETIME)) = MONTH(TODAY() -1);

I remember running across an example before but cannot find it.

[RW9]

Its quite hard to see what your after from that, test data in the form of a datastep and what you want out will help.  Can you not sort the data, then use lag()?  SQL can simply merge these too.  If its an agregate then a where might be better.