IF data set exists

[Ronein]

Hello

Data set QQQ doesn't exist.

Why the following 2 codes give different results.

In way1 nothing happened (It is correct because data set QQQ doesnt exists)

In way2 a data set wanted is created with following information

/****Way1***/
%MACRO if_exists_a;
%if %sysfunc(exist(QQQ)) %then %do;
Data wanted;
SET QQQ;
Run;
%end; 
%MEND;
%if_exists_a;


/***Way2***/
%MACRO if_exists_b;
%if %sysfunc(exist(QQQ)) %then %do;
QQQ;
%end; 
%MEND;
Data wanted;
set %if_exists_b;
Run;

[Kurt_Bremser]

In way 2, the data step will always run and create an empty dataset if QQQ is not there.

[ChrisNZ]

As usual, the answer is in the log.

Have you looked?

[yabwon]

At @ChrisNZ wrote, see the log. And probably, the best way to see the reason why it "works as coded" would be to run it in a new fresh SAS session:

1
2
3    /***Way2***/
4    %MACRO if_exists_b;
5    %if %sysfunc(exist(QQQ)) %then %do;
6    QQQ;
7    %end;
8    %MEND;
9    Data wanted;
10   set %if_exists_b;
ERROR: There is not a default input data set (_LAST_ is _NULL_).
11   Run;

Bart