试试吧，写得不好，好久不用了，对于更大的数据集，可以采用循环语句，时间长了想不起来怎么用了。
令第一个数据集为a,第二个为b
data b; set b;
    if Country="DEU" or Country="FRA" or Country="GBR" then ORIGIN_COUNTRY=Country;
    else ORIGIN_COUNTRY="OTHER";
run;
proc sort data=a; by ORIGIN_COUNTRY;
proc sort data=b; by ORIGIN_COUNTRY;
data b; merge a b; by ORIGIN_COUNTRY; run;

先谢谢你了，但是好像有问题，因为每个country的loading是不一样的。但是还是感谢你哦

个人同意上面的解释
不知道您目前碰到的问题是什么，可以share一下您的code么？

proc sort data=a(rename=(origin_country=country));
by country;
run;
proc sort data=b;
by country;
run;

data c;
merge a(in=x) b(in=y);
by country;
if y then do; if origin_load =. then  origin_load=1.1;output;end;
run;
可能写得不好

proc sql;
create table c as
select b.*,(case when a.ORIGIN_LOAD is null then 1.1 else a.ORIGIN_LOAD end ) as ORIGIN_LOAD
from  ex2 b left join ex1 a on a.ORIGIN_COUNTRY=b.Country;
quit;