Hello, SAS experts!   　 Here is my code:   Data one; A=0; ID_U=1; ID_V=2; Run; 　 　 /* Running the renaming macro */ options macrogen mprint mlogic; %macro rename(lib,dsn,prefixtarget);   select nvar into :num_vars from dictionary.tables where libname="&LIB" and memname="&DSN"; 　 select distinct(name) into :var1- :var%TRIM(%LEFT(&num_vars)) from dictionary.columns where libname="&LIB" and memname="&DSN"; quit; run; 　 　 　 proc datasets library=&LIB; modify &DSN; rename %do i=1 %to &num_vars;   %PUT &&VAR&i; %IF %index(&&var&i,'ID') GT 0 %THEN &&var&i=&prefixtarget._&&var&i.; %end; ; quit; run;   %mend rename; %rename(WORK,ONE,CAL);     So my goal is to rename the variables based on whether the variables name contains a specific text expression(in this case, "ID"). So the final result I expect is:   A CAL_ID_U CAL_ID_V 0 1 2     I have tried many different ways, but none of them work. Can you please tell me where goes wrong?   Thanks! ... View more