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 d

Answer 1

Here's the more complete example that @cmjohns was talking about. It will return 0 if it is empty, -1 if it is missing, and has options to handle deleted observations and where clauses (note that using a where clause can make the macro take a long time on very large datasets).

Usage Notes:

This macro will return the number of observations in a dataset. If the dataset does not exist then -1 will be returned. I would not recommend this for use with ODBC libnames, use it only against SAS tables.

Parameters:

• iDs - The libname.dataset that you want to check.
• iWhereClause (Optional) - A where clause to apply
• iNobsType (Optional) - Either NOBS OR NLOBSF. See SASV9 documentation for descriptions.

Macro definition:

%macro nobs(iDs=, iWhereClause=1, iNobsType=nlobsf, iVerbose=1);
  %local dsid nObs rc;

  %if "&iWhereClause" eq "1" %then %do;
    %let dsID = %sysfunc(open(&iDs));
  %end;
  %else %do;
    %let dsID = %sysfunc(open(&iDs(where=(&iWhereClause))));
  %end;

  %if &dsID %then %do;
    %let nObs = %sysfunc(attrn(&dsID,nlobsf));
    %let rc   = %sysfunc(close(&dsID));
  %end;
  %else %do;
    %if &iVerbose %then %do;
      %put WARNING: MACRO.NOBS.SAS: %sysfunc(sysmsg());      
    %end;
    %let nObs  = -1;
  %end;
  &nObs
%mend;

Example Usage:

%put %nobs(iDs=sashelp.class);
%put %nobs(iDs=sashelp.class, iWhereClause=height gt 60);
%put %nobs(iDs=this_dataset_doesnt_exist);

Results

19
12
-1

Installation

I recommend setting up a SAS autocall library and placing this macro in your autocall location.