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Working with Dates in the SAS System

Displaying Dates

Understanding How SAS Displays Values

To understand how to display the departure dates, you need to understand how SAS displays values in general. SAS displays all data values with a set of directions called a format. By default, SAS uses a standard numeric format with no commas, letters, or other special notation to display the values of numeric variables. Creating SAS Date Values from Calendar Dates shows that printing SAS date values with the standard numeric format produces numbers that are difficult to recognize. To display these numbers as calendar dates, you need to specify a SAS date format for the variable.

SAS date formats are available for the most common ways of writing calendar dates. The DATE9. format represents dates in the form ddMMMyyyy. If you want the month, day, and year to be spelled out, then use the WORDDATE18. format. The WEEKDATE29. format includes the day of the week. There are also formats available for number representations such as the format MMDDYY8., which displays the calendar date in the form mm/dd/yy, or the format MMDDYY10., which displays the calendar date in the form mm/dd/yyyy. Like informat names, each format name ends with a period and contains a width specification that tells SAS how many columns to use when displaying the date value.

Formatting a Date Value

You tell SAS which format to use by specifying the variable and the format name in a FORMAT statement. The following FORMAT statement assigns the MMDDYY10. format to the variable DepartureDate:

format DepartureDate mmddyy10.;

In this example, the FORMAT statement contains the following items:

The following PRINT procedures format the variable DepartureDate in both the two-digit year calendar format and the four-digit year calendar format:

options pagesize=60 linesize=80 pageno=1 nodate;
proc print data=mylib.tourdates;
   title 'Departure Dates in Two-Digit Calendar Format';
   format DepartureDate mmddyy8.;

proc print data=mylib.tourdates;
   title 'Departure Dates in Four-Digit Calendar Format';
   format DepartureDate mmddyy10.;

The following output displays the results:

Displaying a Formatted Date Value

                  Departure Dates in Two-Digit Calendar Format                 1

                   Obs    Country          Date       Nights

                     1    Japan          05/13/00        8  
                     2    Greece         10/17/99       12  
                     3    New Zealand    02/03/01       16  
                     4    Brazil         02/28/01        8  
                     5    Venezuela      11/10/00        9  
                     6    Italy          04/25/01        8  
                     7    Russia         06/03/97       14  
                     8    Switzerland    01/14/01        9  
                     9    Australia      10/24/98       12  
                    10    Ireland        08/27/00        7  
                 Departure Dates in Four-Digit Calendar Format                 2

                   Obs    Country              Date    Nights

                     1    Japan          05/13/2000       8  
                     2    Greece         10/17/1999      12  
                     3    New Zealand    02/03/2001      16  
                     4    Brazil         02/28/2001       8  
                     5    Venezuela      11/10/2000       9  
                     6    Italy          04/25/2001       8  
                     7    Russia         06/03/1997      14  
                     8    Switzerland    01/14/2001       9  
                     9    Australia      10/24/1998      12  
                    10    Ireland        08/27/2000       7  

Placing a FORMAT statement in a PROC step associates the format with the variable only for that step. To associate a format with a variable permanently, use the FORMAT statement in a DATA step.

Assigning Permanent Date Formats to Variables

The next example creates a new permanent SAS data set and assigns the DATE9. format in the DATA step. Now all subsequent procedures and DATA steps that use the variable DepartureDate will use the DATE9. format by default. The PROC CONTENTS step displays the characteristics of the data set MYLIB.TOURDATE.

options yearcutoff=1920 pagesize=60 linesize=80 pageno=1 nodate;

data mylib.fmttourdate;
   set mylib.tourdates;
   format DepartureDate date9.;

proc contents data=mylib.fmttourdate nodetails;

The following output shows that the DATE9. format is permanently associated with DepartureDate:

Assigning a Format in a DATA Step

                                 The SAS System                                1

                             The CONTENTS Procedure

Data Set Name: MYLIB.FMTTOURDATE                        Observations:         10
Member Type:   DATA                                     Variables:            3 
Engine:        V8                                       Indexes:              0 
Created:       14:15 Friday, November 19, 1999          Observation Length:   32
Last Modified: 14:15 Friday, November 19, 1999          Deleted Observations: 0 
Protection:                                             Compressed:           NO
Data Set Type:                                          Sorted:               NO

                  -----Engine/Host Dependent Information-----

Data Set Page Size:         8192                                                
Number of Data Set Pages:   1                                                   
First Data Page:            1                                                   
Max Obs per Page:           254                                                 
Obs in First Data Page:     10                                                  
Number of Data Set Repairs: 0                                                   
filename:                  /SAS_DATA_LIBRARY/fmttourdate.sas7bdat              
Release Created:            8.0001M0                                            
Host Created:               HP-UX                                               
Inode Number:               1498874206                                          
Access Permission:          rw-r--r--                                           
Owner Name:                 user01                                              
File Size (bytes):          16384                                               

              -----Alphabetic List of Variables and Attributes-----
               #    Variable         Type    Len    Pos    Format
               1    Country          Char     11     16          
               2    DepartureDate    Num       8      0    DATE9.
               3    Nights           Num       8      8          

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:

options pagesize=60 linesize=80 pageno=1 nodate;
proc print data=mylib.tourdates;
   title 'Tour Departure Dates';
   format DepartureDate worddate18.;

The following output displays the results:

Overriding a Previously Specified Format

                              Tour Departure Dates                              1

               Obs    Country             DepartureDate    Nights

                 1    Japan                May 13, 2000       8  
                 2    Greece           October 17, 1999      12  
                 3    New Zealand      February 3, 2001      16  
                 4    Brazil          February 28, 2001       8  
                 5    Venezuela       November 10, 2000       9  
                 6    Italy              April 25, 2001       8  
                 7    Russia               June 3, 1997      14  
                 8    Switzerland      January 14, 2001       9  
                 9    Australia        October 24, 1998      12  
                10    Ireland           August 27, 2000       7  

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.

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