data a;
  input class $ score;
  cards;
  01 22
  01 30
  01 50
  02 21
  02 33
  ;
run;
/*分组求每列的最大值、最小值*/
proc sql;
  create table b as
  select *, min(score) as min,max(score) as max
  from a
  group by class;
quit;