管理考研 发表于 2011-8-16 10:06
没有waring 也没有error 就是合并以后没有变量观测值啊
合并以后没有观测值说明两个数据集中trdmnt没有相同的值。
data aaa;
length group $20;
input group $ value1;
cards;
aaa 11
bbb 21
ccc 31
;
data bbb;
length group $10;
input group $ value2;
cards;
aaa 41
bbb 42
ccc 43
ddd 44
;
data ccc;
length group $20;
input group $ value3;
cards;
aaaa 111
bbbb 123
;
*** Normal;
data test1;
merge aaa(in=a) bbb(in=b);
by group;
if a and b;
run;
*** No observation;
data test2;
merge aaa(in=a) ccc(in=b);
by group;
if a and b;
run;
*** You want this?;
data test3;
format group $3.;
merge aaa(in=a) ccc(in=b);
by group;
if a and b;
run;