Using a WHERE Statement to Select Records from a SAS Data Set
If you have an existing SAS data set and you wish to process only certain observations, use a WHERE statement to efficiently select the desired observations.

Which is more efficient?

Code 1:

Data Eligible;
	Set Billing;
	Where Upcase(Eligible)="YES";

Proc Print data=Eligible;
run;

Code 2:

Proc Print data=Billing;
	Where Upcase(Eligible)="YES";
run;