Step-by-Step Programming with Base SAS 9.4, Second Edition, 2nd Edition

Changing Formats Temporarily

If you are preparing a report that requires the date in a different format, then you can

override the permanent format by using a FORMAT statement in a PROC step. For

example, to display the value for DepartureDate in the data set MYLIB.TOURDATES in

the form of month-name dd, yyyy, you can issue a FORMAT statement in a PROC

PRINT step. The following program specifies the WORDDATE18. format for the

variable DepartureDate:

proc print data=mylib.tourdates;

title 'Tour Departure Dates';

format DepartureDate worddate18.;

run;

The following output displays the results:

Figure 15.9 Overriding a Previously Specified Format

The format DATE9. is still permanently assigned to DepartureDate. Calendar dates in

the remaining examples are in the form ddMMMyyyy unless a FORMAT statement is

included in the PROC PRINT step.

Using Dates in Calculations

Sorting Dates

Because SAS date values are numeric variables, you can sort them and use them in

calculations. The following example uses the data set MYLIB.TOURDATES to extract

other information about the Tradewinds Travel data.

Using Dates in Calculations 237

To help determine how frequently tours are scheduled, you can print a report with the

tours listed in chronological order. The first step is to specify the following BY statement

in a PROC SORT step to tell SAS to arrange the observations in ascending order of the

date variable DepartureDate:

by DepartureDate;

By using a VAR statement in the following PROC PRINT step, you can list the departure

date as the first column in the report:

proc sort data=mylib.fmttourdate out=sortdate;

by DepartureDate;

run;

proc print data=sortdate;

var DepartureDate Country Nights;

title 'Departure Dates Listed in Chronological Order';

run;

The following output displays the results:

Figure 15.10 Sorting by SAS Date Values

The observations in the data set SORTDATE are now arranged in chronological order.

Note that there are no FORMAT statements in this example, so the dates are displayed in

the DATE9. format that you assigned to DepartureDate when you created the data set

MYLIB.FMTTOURDATE.

Creating New Date Variables

Because you know the departure date and the number of nights spent on each tour, you

can calculate the return date for each tour. To start, create a new variable by adding the

number of nights to the departure date, as follows:

Return = DepartureDate + Nights;

238 Chapter 15 • Working with Dates in the SAS System