这是一个通用宏，您可以使用它生成源数据集中空列的列表，然后您可以将其传递给 drop 语句.它使用proc格式和proc freq，所以速度相对较快.

Here's a generic macro that you can use to generate a list of the empty columns in the source data set, which you can then pass to a drop statement. It uses proc format and proc freq so it is relatively fast.

%macro findmiss(ds,macvar);
%local noteopt;
%let noteopt=%sysfunc(getoption(notes));
option nonotes;
*ds is the data set to parse for missing values;
*macvar is the macro variable that will store the list of empty columns;
%global &macvar; 
proc format;
  value nmis  .-.z =' ' other='1';
  value $nmis ' '=' ' other='1';
run;
ods listing close;
ods output OneWayFreqs=OneValue(
  where=(frequency=cumfrequency 
  AND CumPercent=100));

proc freq data=&ds;
  table _All_ / Missing ;
  format _numeric_ nmis. 
        _character_ $nmis.;
  run;
ods listing;
data missing(keep=var);
  length var $32.;
  set OneValue end=eof;
    if percent eq 100 AND sum(of F_:) < 1 ;
    var = scan(Table,-1,' ');
run;
proc sql noprint;
  select var into: &macvar separated by " "
  from missing;quit;
option &noteopt.;
%mend;

以下是您可以使用它的方法:

Here is how you might use it:

%findmiss(old,droplist); /*generate the list of empty columns */
data new;
  set old(drop=&droplist);
run;