Eliminate Useless Variables | SAS Code Fragments

The example below shows how to eliminate variables that has only missing values. This code is adapted from SAS-L archives July 2001, week 5. 

data temp;
input x y z;
cards;
1 . 2
2 . 3
4 . 6
;
run;

/***replace 'temp' below with the name of your data set****/
%let have = temp;

/**Do not change anything below**/

*discover min and max for all numeric vars. ;
proc means data=&have noprint ;  
  output out=_temp_1; 
  run;
*organize as one observation for each numeric var. ;
proc transpose data=_temp_1 out=_temp_2 name = _stat_ ; 
  id _stat_; 
run;
/**Create the list of variables to be dropped***/
proc sql noprint;  
   select _stat_ into :dropList separated by ' '
   from _temp_2
   where min = max and max = . ;
quit;

/*Replace 'temp1' with the name of your (new) dataset*/
data temp1 ( drop=&dropList ); 
  set &have;
run;

proc print data=temp1;
run;
   
Obs    x    z
 1     1    2
 2     2    3
 3     4    6