Free download SAS master piece, must read
http://www2.sas.com/proceedings/sugi31/246-31.pdf
Abstract
You are relatively new to SAS and interested in writing SAS code. You have probably written DATA step code; some
works, some doesn't, sometimes you know why, and sometimes you don't. If this describes you, then this talk is for
you.
You are a programmer, new to SAS. The DATA step language looks similar to PL1 and has some characteristics
that look like languages you are familiar with. However, after learning the syntax your code feels awkward and you
feel like you are fighting the system. The DATA step has been very well designed, but it is different, and it is worth
learning how it works, if you want elegant code, this talk is for you.
Even people who have been SAS programmers who have been working with SAS for years should find, an "Ah ha,
so that's why", in this talk.