How to delete and import datasets dynamically in SAS?

Question

I have four comma separated files: mar2009.txt, mar2010.txt, mar2011.txt and mar2012.txt

I am trying to cleanse my library and import those datasets dynamically:

libname my "C:\Users\Owner\Desktop\SAS\";

data A; // I do not this step but if I do not use it the the "do" becomes red in color
do i = 2009 to 2012;

proc datasets library=my;
delete mar.&i;
run;

proc import out=my.mar.&i datafile="C:\Users\Owner\Desktop\SAS\mar.&i.txt" dbms=dlm replace;
delimiter='2c'x;
getnames=yes;
datarow=2;
run;

end;
run;

Answer 1

To answer your question at a fundamental level, you don't need to "cleanse" the dataset just because you are reimporting it; it will automatically be replaced.

You could write a macro to do the import, like so:

%macro import_myfile(i=);
proc import file="...whatever...\mar&i.txt" out=mar_&i. dlm=',' replace;
run;
%mend import_myfile;

%import_myfile(i=2009);
%import_myfile(i=2010);
%import_myfile(i=2011);
%import_myfile(i=2012);

You could write a loop to execute that from 2009 to 2012, but it's not worth the code if it's just four runs. If you have a dynamic number to execute, and those values are in a dataset, you could do it this way:

data data_torun;
input filenum;
datalines;
2009
2010
2011
2012
;;;;
run;

proc sql;
select cats('%import_myfile(i=',filenum,')') into :listtorun 
 separated by ' '
 from data_torun;
quit;

&listtorun.;
*this will become the same four calls as above;

It is typically better to have data like this kept in dataset form rather than in code when it potentially could change (even in a loop). That way you could store this in a text file and read it in.