Merge question

joe4444 — Wed, 16 May 2012 22:46:51 GMT

I have a simple merging question that should be an easy answer, but I can not figure it out. Here is the data. Thanks.

Dataset1

ID Var1

1 Yes

3 No

Dataset2

ID Var1

2 Yes

data dataset3;

merge dataset1 (in=a) dataset2 (in=b);

by ID;

if a;

run;

Dataset3

ID Var1

1 Yes

2 Yes

3 No

Why does ID = 2 not have "Yes" replace the blanks in Var1 for both records?

Thanks.

Re: Merge question

Tom — Wed, 16 May 2012 23:48:19 GMT

Because only one record with a YES was provided from the second dataset. So on the second observation for ID=2 only dataset1 is contributing a value.

Many to One merges like this only work when the non-key variables do not overlap.