options nosource nomprint nomlogic nosymbolgen;
 
%macro reorder(dsn); 
	/* Get the variables names to a dataset using proc contents and keeping the variable name only */ 
	proc contents data=&dsn
	out=varnames(keep=name) noprint;
	run;

	/* It is very much important that you UPCASE or LOWCASE the variable names...
	otherwise you get a different order...Remove this datastep and see for yourself... */ 
	data varnames;
		set varnames;
		name=lowcase(name);
	run;

/* Sort the variable names in alphabetical order */ 
proc sort data=varnames; 
by name;
run;

/* Get the observation count */ 

data _null_;
	set varnames nobs=num;
	call symput('obscnt',num);/* Get the observation count */ 
	call symput(compress('macvar'||_n_),trim(left(name))); /* Get the variable names into macro variables */ 
run;

%let obscnt=&obscnt; /*remove the leading and trailing blankspaces generated when numeric is converted to Best12. format */ 
%put obscnt=&obscnt;
/*Please NOTE that the step of getting all variable names into a macro variable could be simply done by using SQL instead of a macro
proc sql noprint;
select trim(left(name)) into:macvar separated by ' '
from varnames;
quit;

and the next datastep simply

data &dsn;
retain &macvar;
set &dsn;
run;

But the cons here is that if there are too many variables and the total length of all the names put together crosses 32767 bytes the SQL approach would'nt work...
*/ 

 
data &dsn;
retain %do i=1 %to &obscnt; 
            &&macvar&i  /* NOTE: there should be a blank space after &&macvar&i to separate the variable names by space
                 eg. retain subject a b c; NOTE: NO semicolon should be typed here*/ 
       %end;;
set &dsn;
run;
%mend reorder;

/* Example dataset with variety of variable names */ 
data flags; 
set sashelp.flags; 
a=2; 
b=4; 
_common=10; 
Cool=30; 
SubJecT=40; 
run; 

ods listing close;
ods html body="C:\Reorder.html";
title 'Order of the Variable Before Re-ordering';
proc contents data=flags; run;

%reorder(flags); 

title 'Order of the Variable after Re-ordering';
proc contents data=flags; run;
ods html close;
ods listing;

http://sastechies.blogspot.com/2009/11/sas-macro-to-reorder-dataset-variables.html

SAS Macro to reorder dataset variables in alphabetical order...

SAS