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Date Functions in SAS

Function	Definition
TODAY	The TODAY function returns the current date as a SAS date value.
DATEPART	The DATEPART function extracts the date portion from a datetime value and returns it as a SAS date value.
YEAR	The YEAR function extracts the year from a SAS date value.
MONTH	The MONTH function extracts the month from a SAS date value.
DAY	The DAY function extracts the day of the month from a SAS date value.
MDY	The MDY function creates a SAS date value from the given month, day, and year values.
INTCK	The INTCK function calculates the number of intervals (e.g., days, months, years) between two dates.
INTNX	The INTNX function increments a date value by a specified number of intervals (e.g., days, months, years).

Create sample data

* Create a dataset with sample date and datetime values ;
data date_data;
   infile datalines truncover;
   input start_date :date9. end_date :date9. datetime_val :datetime19.;
   format start_date end_date date9. datetime_val datetime19.;
datalines;
01JAN2023 31DEC2023 01JAN2023:12:00:00
15MAR2022 20SEP2022 15MAR2022:08:30:00
05MAY2021 10AUG2021 05MAY2021:14:15:00
;
run;

Examples for TODAY Function

The TODAY function returns the current system date as a SAS date value.
In the example below, the `current_date` variable stores the system date.

* Get the current system date ;
data today_example;
   set date_data;
   current_date = today();
   format current_date date9.;
run;

Examples for DATEPART Function

The DATEPART function extracts the date portion from a datetime value.
In the example below, the `extracted_date` variable contains only the date part of the `datetime_val` variable.

* Extract the date portion from a datetime value ;
data datepart_example;
   set date_data;
   extracted_date = datepart(datetime_val);
   format extracted_date date9.;
run;

Examples for YEAR, MONTH, and DAY Functions

The YEAR, MONTH, and DAY functions extract the respective parts from a SAS date value.
In the example below, `year`, `month`, and `day` are extracted from the `start_date` variable.

* Extract year, month, and day from a date value ;
data year_month_day_example;
   set date_data;
   year = year(start_date);
   month = month(start_date);
   day = day(start_date);
run;

Examples for MDY Function

The MDY function creates a SAS date value from month, day, and year values.
In the example below, a new SAS date value is created using the MDY function.

* Create a date value from month, day, and year ;
data mdy_example;
   set date_data;
   new_date = mdy(month(start_date), day(start_date), year(start_date));
   format new_date date9.;
run;

Examples for INTCK Function

The INTCK function calculates the number of intervals between two dates.
In the example below, the number of months between `start_date` and `end_date` is calculated.

* Calculate the number of months between two dates ;
data intck_example;
   set date_data;
   months_between = intck('month', start_date, end_date);
run;

Examples for INTNX Function

The INTNX function increments a date value by a specified number of intervals.
In the example below, the `next_month` variable contains the date one month after `start_date`.

* Increment a date by one month ;
data intnx_example;
   set date_data;
   next_month = intnx('month', start_date, 1);
   format next_month date9.;
run;