How to Add Days to Date in SAS (With Example)

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The easiest way to add days to a date variable in SAS is to use the INTNX function.

This function uses the following basic syntax:

INTNX(interval, start_date, increment)

where:

• interval: The interval to add to date (day, week, month, year, etc.)
• start_date: Variable that contains start dates
• increment: The number of intervals to add

The following example shows how to use this syntax in practice.

Example: Add Days to Date in SAS

Suppose we have the following dataset in SAS that shows the total sales made on various days at some store:

/*create dataset*/
data data1;
    input month day year sales;
    datalines;
10 15 2022 45
10 19 2022 50
10 25 2022 39
11 05 2022 14
12 19 2022 29
12 23 2022 40
;
run;

/*create second dataset with date formatted*/
data data2;
  set data1;
  date=mdy(month,day,year);
  format date mmddyy10.;
  drop month day year;
run;

/*view dataset*/
proc print data=data2;

We can use the following code to create a new column called date_plus5 that adds five days to the values in the date column:

/*create new dataset with column that adds 5 days to date*/
data data3; 
  set data2; 
  date_plus5=intnx('day', date, 5); 
  format date_plus5 mmddyy10.;
run;

/*view dataset*/
proc print data=data3;

Notice that the new column called date_plus5 contains the values in the date column with fives days added to them.

Note that you can also subtract days by simply using a negative value in the INTNX function.

For example, we can use the following code to subtract five days from each value in the date column:

/*create new dataset with column that subtracts 5 days to date*/
data data3; 
  set data2; 
  date_minus5=intnx('day', date, -5); 
  format date_minus5 mmddyy10.;
run;

/*view dataset*/
proc print data=data3;

Notice that the new column called dateminus5 contains the values in the date column with fives days subtracted from them.

Note: You can find the complete documentation for the SAS INTNX function here.

Additional Resources

The following tutorials explain how to perform other common tasks in SAS:

How to Normalize Data in SAS
How to Identify Outliers in SAS
How to Create Frequency Tables in SAS