data have;
input make $ mpg rep78 price foreign;
datalines;
AMC 22 3 2930 0
AMC 17 3 3350 0
AMC 22 . 2640 0
Audi 17 5 2830 1
Audi 23 3 2070 1
BMW 25 4 2650 1
Buick 20 3 3250 0
Buick 15 4 4080 0
Buick 18 3 3670 0
Buick 26 . 2230 0
Buick 20 3 3280 0
Buick 16 3 3880 0
Buick 19 3 3400 0
Cad. 14 3 4330 0
Cad. 14 2 3900 0
Cad. 21 3 4290 0
Chev. 29 3 2110 0
Chev. 16 4 3690 0
Chev. 22 3 3180 0
Chev. 22 2 3220 0
Chev. 24 2 2750 0
Chev. 19 3 3430 0
Datsun 23 4 2370 1
Datsun 35 5 2020 1
Datsun 24 4 2280 1
Datsun 21 4 2750 1
;
run;

%macro high(var);
        proc sql noprint;
                select distinct make into :make_max separated by ' and '
                from have
                having &var eq max(&var);
        quit;

        %if %SYSFUNC(FIND(&make_max,%STR( ))) NE 0 %then %do;
                %put &make_max have the highest &var..;
        %end;
        %else %do;
                %put &make_max has the highest &var..;
        %end;
%mend;

%high(mpg);
%high(rep78);

虽然好几句语句意思不太明白，但是非常感谢！！！我在自己研究下