It is not difficult to learn SAS,
The key is to master RETAIN and MERGE
RETAIN abandons the old friend only when he gets a new one,
First.VAR makes a great difference by it's "1".
MERGE likes to join hands to hands (of datasets),
It is "BY" to keep every thing in order.
SET does his job by "FIRST COME, FIRST SERVE",
It is also "BY" to make "interleaving" a reality.
If you love him, then "KEEP",
If you hate him, then "DROP".
"IN" tells us some one is coming,
"END" signals the last observation.
SAS was born in 1960,1,1
She counts her age by days.
INFORMATS gets in all all "clothes",
FORMAT represents her own wishes.
Using "INPUT", we get numbers;
