data a;
input name$ birth $ income;
cards;
张三 19870110 3000
. . 5000
. . 4000
李四 19830312 7000
. . 8000
. . 2500
. . 4000
赵五 19881213 2000
. . 6000
;
run;
data b;
set a;
length name1$10. birth1$10.;
retain name1 birth1;
if first.id then do;
name1='';
birth1='';
end;
if name ^='' then name1 = name;
if birth^='' then birth1 = birth;
keep name1 birth1 income;
run;