02-18-2016 10:24 AM
If <condition> then <code> is part of Base SAS
%if <condition> %then <code> is part of Macro Programming
Please refer to the documentation on what each of those products are and what they do, basically Base SAS is the programming language, Macro is an additional component to generate text code.
02-18-2016 10:59 AM
Here is a very strong hint: If you are comparing dataset variable values use if/then/else.
If you are conditionally creating program code you likely are looking at %if/%then/%else.
02-18-2016 10:40 AM
Have you looked at the section "Comparisons" and Example 1 ("Contrasting the %IF-%THEN/%ELSE Statement with the IF-THEN/ELSE Statement") of the %IF-%THEN/%ELSE Statement documentation?
Or have you tried to use either of the two statements and it didn't work? If so, please feel free to report the specific problem you encountered. It's probably most helpful for you to get an explanation that is related to your own program code.