proc sql;
select coalesce(a.x, b.x) as x, a.m, b.n from
b as b full join A as a  on A.x = b.x ;quit;

多谢楼上的，用下试试去

学习啦！顶！

问下二楼的，如果一步把多个表链接起来，帮忙看下我下面的写法有没有问题，多谢了！
data a;
input x m;
cards;
11 61
22 62
33 63
;
run;

data b;
input x n;
cards;
33 73
22 72
44 74
;
run;

data c;
input x p;
cards;
55 85
33 83
22 82
;
run;

data d;
input x q;
cards;
55 95
33 93
22 92
66 96
;
run;
/*SQL全联接*/
proc sql;
   create table full as select
      coalesce(a.x,b.x,c.x,d.x) as x,
      a.*, b.n, c.p, d.q
   from a
      full join b on coalesce(a.x,b.x)=b.x
      full join c on coalesce(a.x,b.x,c.x)=c.x
      full join d on coalesce(a.x,b.x,c.x,d.x)=d.x;
quit;

另外，接上楼问下，如果两个表a有变量x y z, 表b有变量x m n;现在把两个表连起来
proc sql;
   create table c as select
     a.*, b.m, b.n
from a full join b on a.x=b.x;
quit;
现在当b中变量很多时，一个一个写很麻烦，如果用b.*又会提示b.x和a.x重合，请问下如何能简写又不提示出错？！非常感谢。