data a;
input name $ subject $ score;
cards;
david chinese 89
david english 90
david english 90 /* (这个重复了)*/
david maths 78
david maths 78 /* (这个重复了)*/
david maths 78 /* (这个重复了)*/
jack chinese 99
jack chinese 99 /* (这个重复了)*/
jack english 70
;
proc sort;
by name subject;
data b;
set a;
by name subject;
if last.name or last.subject;
run;