How to detect how many observations in a dataset (or if it is empty), in SAS?

Question

I wonder if there is a way of detecting whether a data set is empty, i.e. it has no observations. Or in another saying, how to get the number of observations in a specific data set.

So that I can write an If statement to set some conditions.

Thanks.

Answer 1

It's easy with PROC SQL. Do a count and put the results in a macro variable.

proc sql noprint;
 select count(*) into :observations from library.dataset;
quit;

Answer 2

There are lots of different ways, I tend to use a macro function with open() and attrn(). Below is a simple example that works great most of the time. If you are going to be dealing with data views or more complex situations like having a data set with records marked for deletion or active where clauses, then you might need more robust logic.

%macro nobs(ds);
    %let DSID=%sysfunc(OPEN(&ds.,IN));
    %let NOBS=%sysfunc(ATTRN(&DSID,NOBS));
    %let RC=%sysfunc(CLOSE(&DSID));
    &NOBS
%mend;

/* Here is an example */
%put %nobs(sashelp.class);