一眼瞬间 发表于 2010-3-19 09:33 
有很多组数据，
现在想选择每组的第一组数据。
用什么办法选择呢？
I guess you want to get the first observation in each and every group. Here is an example.
data t1;
do i = 1 to 100;
group=mod(i,30);
output;
end;
run;
proc sort data=t1; by group; run;
data t2;
set t1;
by group;
if first.group then output;
run;
proc print; run;
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