• identify the type of information provided by automatic macro variables
• reference an automatic macro variable
• identify when automatic macro variable references are resolved.

Automatic Macro Variables

Whenever you invoke the SAS System, automatic macro variables are created that provide such information as the

• date or time a SAS job or session began executing
• release of SAS software you are running
• name of the most recently created SAS data set
• abbreviation for your host operating system.

To demonstrate how to use automatic macro variables, let's modify the following program to include an automatic macro variable. This program creates and prints a data set that has information about temporary employees who were hired in November.

     title 'Temporary Employees Hired in November';
     data hrd.tempnov;
        set hrd.temp;
        if month(begindate)=11;
     run;
     proc print data=hrd.tempnov;
     run;

The program includes the MONTH function to extract the month value from the data set variable BeginDate. For more information about the MONTH function, refer to the lesson Transforming Data with SAS Functions. Now, suppose you want to add a FOOTNOTE statement to this program to specify the date that the program is executed.

The SYSDATE Macro Variable

The automatic macro variable SYSDATE can provide the date that the program is executed. The SYSDATE macro variable supplies the date when a SAS job began executing or when you began your SAS session. The date is displayed by using the DATE7. format. For example, in a job that begins executing on November 30, 1999, the value of SYSDATE is 30NOV99.

You can include this date in the footnote of your report by referencing the SYSDATE macro variable in the FOOTNOTE statement. To reference any macro variable, you specify the macro variable name preceded by an ampersand.

     &SYSDATE

So, you write the FOOTNOTE statement as follows:

     footnote "Report Run on &sysdate";

Prior to DATA step compilation, SAS software resolves the macro variable reference by replacing &SYSDATE with the value of the SYSDATE macro variable.

So your FOOTNOTE statement . . .

     footnote "Report Run on &sysdate";

. . . is processed as follows, if your session begins on November 30, 1999:

     footnote "Report Run on 30NOV99";

Then, after your program compiles successfully, the program statements are executed, and your new data set is printed with the specified title and footnote.