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Dates, Times, and Intervals

About SAS Date, Time, and Datetime Values

Definitions

SAS date value

is a value that represents the number of days between January 1, 1960, and a specified date. SAS can perform calculations on dates ranging from A.D. 1582 to A.D. 19,900. Dates before January 1, 1960, are negative numbers; dates after are positive numbers.

  • SAS date values account for all leap year days, including the leap year day in the year 2000.

  • SAS date values can reliably tell you what day of the week a particular day fell on as far back as September 1752, when the calendar was adjusted by dropping several days. SAS day-of-the-week and length-of-time calculations are accurate in the future to A.D. 19,900.

  • Various SAS language elements handle SAS date values: functions, formats, and informats.

SAS time value

is a value representing the number of seconds since midnight of the current day. SAS time values are between 0 and 86400.

SAS datetime value

is a value representing the number of seconds between January 1, 1960 and an hour/minute/second within a specified date.

The following figure shows some dates written in calendar form and as SAS date values.

How SAS Converts Calendar Dates to SAS Date Values

[How SAS Converts Calendar Dates to SAS Date Values]

Two-Digit and Four-Digit Years

SAS software can read two-digit or four-digit year values. If SAS encounters a two-digit year, the YEARCUTOFF= option can be used to specify which century within a 100- year span the two-digit year should be attributed to. For example, YEARCUTOFF=1950 means that two-digit years 50 through 99 correspond to 1950 through 1999, while two-digit years 00 through 49 correspond to 2000 through 2049. Note that while the default value of the YEARCUTOFF= option in SAS 9 is 1920, you can adjust the YEARCUTOFF= value in a DATA step to accommodate the range of date values you are working with at the moment. To correctly handle 2-digit years representing dates between 2000 and 2099, you should specify an appropriate YEARCUTOFF= value between 1901 and 2000. For more information, see the YEARCUTOFF= System Option in SAS Language Reference: Dictionary.

The Year 2000


Using the YEARCUTOFF= System Option

SAS software treats the year 2000 like any other leap year. If you use two-digit year numbers for dates, you'll probably need to adjust the default setting for the YEARCUTOFF= option to work with date ranges for your data, or switch to four-digit years. The following program changes the YEARCUTOFF= value to 1950. This change means that all two digit dates are now assumed to fall in the 100-year span from 1950 to 2049. 

options yearcutoff=1950;
data _null_;
   a='26oct02'd;
   put 'SAS date='a;
   put 'formatted date='a date9.;
run;

The PUT statement writes the following lines to the SAS log: 

SAS date=15639
formated date=26OCT2002

Note:   Whenever possible, specify a year using all four digits. Most SAS date and time language elements support four digit year values.  [cautionend]


Example: How YEARCUTOFF= Affects Two and Four-Digit Years

The following example shows what happens with data that contains both two and four-digit years. Note how the YEARCUTOFF= option is set to 1920. 

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

data schedule;
   input @1 jobid $ @6 projdate mmddyy10.;
   datalines;
A100 01/15/25
A110 03/15/2025
A200 01/30/96
B100 02/05/00
B200 06/15/2000
;

proc print data=schedule;
   format projdate mmddyy10.;
run;

The resulting output from the PROC PRINT statement looks like this:

Output from The Previous DATA Step Showing Four-Digit Years That Result from Setting YEARCUTOFF= to 1920 

                                 The SAS System         1
                           Obs    jobid      projdate

                            1     A100     01/15/1925
                            2     A110     03/15/2025
                            3     A200     01/30/1996
                            4     B100     02/05/2000
                            5     B200     06/15/2000

Here are some facts to note in this example:

As you can see, specifying a two-digit year might or might not result in the intended century prefix. The optimal value of the YEARCUTOFF= option depends on the range of the dates that you are processing.

In Releases 6.06 through 6.12 of SAS, the default value for the YEARCUTOFF= system option is 1900; starting with SAS 7, the default value is 1920.

For more information on how SAS handles dates, see the section on dates, times, and datetime values.


Practices That Help Ensure Date Integrity

The following practices help ensure that your date values are correct during all the conversions that occur during processing:

Note:   The YEARCUTOFF= option has no effect on dates that are already stored as SAS date values.  [cautionend]

Working with SAS Dates and Times


Informats and Formats

SAS converts date, time, and datetime values back and forth between calendar dates and clock times with SAS language elements called formats and informats.

SAS can read date and time values that are delimited by the following characters:

! # $ % & ( ) * + - . / : ; < = > ? [ \ ] ^ _ { | } ~

The blank character can also be used.

Only one delimiter can be used for a date. Otherwise, an error message is written to the SAS log. For example, 01/Jan/2007 uses a single delimiter, and can be read by SAS. In the case of 01-Jan/2007, two different delimiters separate the parts of the date, which results in an error message.


Date and Time Tools by Task

The following table correlates tasks with various SAS language elements that are available for working with time and date data.

Tasks with Dates and Times, Part 1
Task Type of Language Element Language Element Input Result
Write SAS date values in recognizable forms Date formats DATE. 14686 17MAR00


DATE9. 14686 17MAR2000


DAY. 14686 17


DDMMYY. 14686 17/03/00


DDMMYY10. 14686 17/03/2000


DDMMYYB. 14686 17 03 00


DDMMYYB10. 14686 17 03 2000


DDMMYYC. 14686 17:03:20


DDMMYYC10. 14686 17:03:2000


DDMMYYD. 14686 17-03-00


DDMMYYD10. 14686 17-03-2000


DDMMYYN. 14686 17032000


DDMMYYN6. 14686 170300


DDMMYYP. 14686 17.03.00


DDMMYYP10. 14686 17.03.2000


DDMMYYS. 14686 17/03/00


DDMMYYS10. 14686 17/03/2000


DOWNAME. 14686 Friday


JULDAY. 14686 77


JULIAN. 14686 00077


MMDDYY. 14686 03/17/00


MMDDYY10. 14686 03/17/2000


MMDDYYB. 14686 03 17 00


MMDDYYB10. 14686 03 17 2000


MMDDYYC. 14686 03:17:00


MMDDYYC10. 14686 03:17:2000


MMDDYYD. 14686 03-17-00


MMDDYYD10. 14686 03-17-2000


MMDDYYN. 14686 031700


MMDDYYN8. 14686 03172000


MMDDYYP. 14686 03.17.00


MMDDYYP10. 14686 03.17.2000


MMDDYYS. 14686 03/17/00


MMDDYYS10. 14686 03/17/2000


MMYY. 14686 03M2000


MMYYC. 14686 03:2000


MMYYD. 14686 03-2000


MMYYN. 14686 032000


MMYYP. 14686 03.2000


MMYYS. 14686 03/2000


MONNAME. 14686 March


MONTH. 14686 3


MONYY. 14686 MAR2000


PDJULG. 14686 2000077F


PDJULI. 14686 0100077F


WEEKDATE. 14686 Friday, March 17, 2000


WEEKDAY. 14686 6


WORDDATE. 14686 March 17, 2000


WORDDATX. 14686 17 MARCH 2000

Quarter formats QTR. 14686 1


QTRR. 14686 I

Time formats TIME. 14686 4:04:46


TIMEAMPM. 14686 4:04:46 AM


TOD. 14686 04:04:46

Year formats YEAR. 14686 2000


YYMM. 14686 2000M03


YYMMC. 14686 2000:03


YYMMD. 14686 2000-03


YYMMP. 14686 2000.03


YYMMS. 14686 2000/03


YYMMN. 14686 200003


YYMMDD. 14686 00-03-17


YYMON. 14686 2000MAR

Year/Quarter formats YYQ. 14686 2000Q1


YYQC. 14686 2000:1


YYQD. 14686 2000-1


YYQP. 14686 2000.1


YYQS. 14686 2000/1


YYQN. 14686 20001


YYQR. 14686 2000QI


YYQRC. 14686 2000:I


YYQRD. 14686 2000-I


YYQRP. 14686 2000.I


YYQRS. 14686 2000/I


YYQRN. 14686 III

Tasks with Dates and Times, Part 2
Task Type of Language Element Language Element Input Result
Date Tasks


Read calendar dates as SAS date

Note: YEARCUTOFF=1920

 Date informats DATE. 17MAR2000 14686


DATE9. 17MAR2000 14686


DDMMYY. 170300 14686


DDMMYY8. 17032000 14686


JULIAN. 0077 14686


JULIAN7. 2000077 14686


MMDDYY. 031700 14686


MMDDYY10. 03172000 14686


MONYY. MAR00 14670


YYMMDD. 000317 14686


YYMMDD10. 20000317 14686


YYQ. 00Q1 14610
Create date values from pieces Date functions DATEJUL 2000077 14686


DATETIME '17MAR2000'D,

00,00,00

 1268870400


TIME 14,45,32 53132


MDY 03,17,00 14686


MDY 03,17,2000 14686


YYQ 00,1 14610
Extract a date from a datetime value Date functions DATEPART '17MAR00:00:00

'DT

 14686
Return today's date as a SAS date Date functions DATE() or TODAY() (equivalent) ( ) SAS date for today
Extract calendar dates from SAS Date functions DAY 14686 17


HOUR 14686 4


JULDATE 14686 77


JULDATE7 14686 2000077


MINUTE 14686 4


MONTH 14686 3


QTR 14686 3


SECOND 14686 46


WEEKDAY 14686 6


YEAR 14686 2000
Write a date as a constant in an expression SAS date constant 'ddmmmyy'd

or

'ddmmmyyyy'

 '17mar00'd


'17mar2000'd




14686
Write today's date as a string SYSDATE automatic macro variable SYSDATE &SYSDATE Date at time of SAS initialization in DDMMMYY

SYSDATE9 SYSDATE9 &SYSDATE9 Date at time of SAS initialization in DDMMMYYYY
Time Tasks


Write SAS time values as time values time formats HHMM. 53132 14:46


HOUR. 53132 15


MMSS. 53132 885


TIME. 53132 14:45:32


TIMEAMPM. 53132 2:45:32 PM


TOD. 53132 14:45:32
Read time values as SAS time values Time informats TIME. 14:45:32 53132
Write the current time as a string SYSTIME automatic macro variable SYSTIME &SYSTIME Time at moment of execution in HH:MM
Return the current time of day as a SAS time value Time functions TIME( ) ( ) SAS time value at moment of execution in NNNNN.NN
Return the time part of a SAS datetime value Time functions TIMEPART SAS datetime value in NNNNNNNNNN.N SAS time value part of date value in NNNNN.NN
Datetime Tasks


Write SAS datetime values as datetime values Datetime formats DATEAMPM 1217083532 26JUL98:02:45 PM


DATETIME 1268870400 17MAR00:00:00

:00
Read datetime values as SAS datetime values Datetime informats DATETIME 17MAR00:00:00:00 1268870400
Return the current date and time of day as a SAS datetime value Datetime functions DATETIME() () SAS datetime value at moment of execution in NNNNNNNNNN.N
Interval Tasks


Return the number of specified time intervals that lie between the two date or datetime values Interval functions INTCK week 2

01aug60

01jan01

 1055
Advances a date, time, or datetime value by a given interval, and returns a date, time, or datetime value Interval functions INTNX day

14086

01jan60

 14086

SAS also supports international formats and informats that are equivalent to some of the most commonly used English-language date formats and informats. For details, see the SAS formats and informats in SAS Language Reference: Dictionary.

Examples


Example 1: Displaying Date, Time, and Datetime Values as Recognizable Dates and Times

The following example demonstrates how a value might be displayed as a date, a time, or a datetime. Remember to select the SAS language element that converts a SAS date, time, or datetime value to the intended date, time or datetime format. See the previous tables for examples.

Note:   

  [cautionend]

This program uses the DATETIME, DATE, and TIMEAMPM formats to display the value 86399 to a date and time, a calendar date, and a time. 

data test;
   Time1=86399;
   format Time1 datetime.;
   Date1=86399;
   format Date1 date.;
   Time2=86399;
   format Time2 timeampm.;
run;
proc print data=test;
   title  'Same Number, Different SAS Values';
   footnote1 'Time1 is a SAS DATETIME value';
   footnote2 'Date1 is a SAS DATE value';
   footnote3 'Time2 is a SAS TIME value'.;
run;
footnote;

Datetime, Date and Time Values for 86399 

                       Same Number, Different SAS Values               1

               Obs         Time1           Date1        Time2

                1     01JAN60:23:59:59    20JUL96    11:59:59 PM
 
 
  
                         Time1 is a SAS DATETIME value
                           Date1 is a SAS DATE value
                           Time2 is a SAS TIME value.

Example 2: Reading, Writing, and Calculating Date Values

This program reads four regional meeting dates and calculates the dates on which announcements should be mailed. 

data meeting;
   
   input region $ mtg : mmddyy8.;
   sendmail=mtg-45;
   datalines;
N  11-24-99
S  12-28-99
E  12-03-99
W  10-04-99
;

proc print data=meeting;
   format mtg sendmail date9.;
   title 'When To Send Announcements';
run;

Calculated Date Values: When to Send Mail 

                          When To Send Announcements                        

             Obs    region          mtg     sendmail

              1       N       24NOV1999    10OCT1999
              2       S       28DEC1999    13NOV1999
              3       E       03DEC1999    19OCT1999
              4       W       04OCT1999    20AUG1999

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