I want to make a union of all datasets from 2010-2019 whcih are named like students_201001, students_201002....students_201012.....students_201905.   I was using a nested loop one for year and other for moth, but it is not working:   %macro join; %Do i=2010 %to 2019; %DO j=01 %TO 12; data append_recov_&i&j; set chi_perf.perf_chi_&i run; %end; %end; %mend; %join;   Please help! ... View more