%macro a1;
data a1;
set sasuser.zy;
keep &b1 group;
proc sort data=a1;
by group;
run;
proc means n mean std max min median maxdec=2;/*定义了表A的小数点后位数,不能用于其它表*/
var &b1;
by group;
OUTPUT OUT=b4 n=N mean=MEAN std=STD max=MAX min=MIN median=MEDIAN ;