方法四：暴力方式

b=lag(a)
delete the first row
original a is your final b
original b is your final a

data a;
input a @@;
cards;
1 4 3 4 5 6
;
run;
data a;
set a;
n+1;
run;
proc sort data=a;
by  descending n;
run;
data a;
set a;
b=lag(a);
run;
proc sort data=a out=ab;
by n;
run;
data ab;
set ab;
drop n;
run;

proc print;
run;

真的是小巫见大巫了；得好好学习了哦