就是根据一个变量中的所有不同值生成子集。请问用宏该怎么写呢？

It needs two passes to have it done. First one needs get unique city name list. Second, based upon the result proper sas program needs to be  generated. If a city name will be a data set name, it must be concur with SAS name convention.



data city;
  length city $20;
  do city='shanghai','bejing','nanjin','tianjing';
    n=ceil(ranuni(123)*10);
        do i=1 to n;
        othervar=rannor(123);
        output;
        end;
  end;
run;



%macro split(dsn_in=);
proc sql noprint;
  select distinct city into: city1 - : city3000
  from city;
  %let n=&sqlobs;
  quit;


  data %do i=1 %to &n;
         &&city&i
           %end;
           ;
           set &dsn_in;
       if city="&city1" then output &city1;
           %do i=2 %to &n-1;
             else if city="&&city&i" then output &&city&i;
           %end;
       else output &&city&n;
  run;
%mend;
options mprint;
%split(dsn_in=city);

谢谢你的方案，不过还没有看懂，正在学习中。。。。

tip:   Don't learn SAS macro until you have solid data step programming skill.

data city;
  length city $20;
  do city='shanghai','bejing','nanjin','tianjing';
    n=ceil(ranuni(123)*10);
        do i=1 to n;
        othervar=rannor(123);
        output;
        end;
  end;
run;

proc sql noprint;
   select distinct strip("_"||city) into : citylist separated by " "
    from city;
quit;

%put &citylist;


data _null_;
    length code $1000;
        retain code;
    set city end=last;
        by city notsorted;
        if _n_=1 then code="data &citylist; set city;";
        if first.city then do;
           count+1;
       if count=1 then code=strip(code)||"if city="||quote(strip(city))||" then output _"||strip(city)||";";
           else if count>1 then code=strip(code)||"else if city="||quote(strip(city))||" then output _"||strip(city)||";";
        end;
    if last then do;
         code=strip(code)||" run;";
                put code=;
                call execute(code);
        end;

run;