#Calculate dates subtract how to

With aplogies to falcon69, using the INTCK function to calculate the number of hours between two dates is incorrect because the HOUR interval is only applicable to times.Īlternately, you can use the DATDIF() function to calculate the difference, but unless you need to use 30-day standard months and 360-day standard years, this is identical to subtracting start_date from end_date. In this specific case, this isn't an issue, but it can cause confusion if you are using date intervals other than days. Using the INTCK() function for something this simple is overkill, as it counts interval boundaries and not necessarily contiguous days. If you want to consider people who (in this case) are admitted and discharged on the same date as having a duration of 1 day, then the formula becomes duration=end_date-start_date+1. In general, the difference between two SAS dates in days can most easily be calculated as duration=end_date - start_date. This makes it easy to do simple calculations involving dates. The first thing to remember is that 'SAS-formatted dates' are stored as an integer representing numer of days relative to January 1, 1960. * return the higher of two values: calculated interval or 1 */ĭur = max(intck('day',date_1,date_2), 1) If your data are such that any record with a hospital admission represents at least a 1-day stay (for reporting purposes), then your formula might be: For example, a patient who is admitted and charged on the same day might count as a 1-day stay, and a patient who is discharged on the second day might still count as a 1-day stay - so you might need to modify the formula to add 1 in the case of a same-day discharge. this example of using INTCK with datetime variables to calculate a day interval.įor hospital stays, you might have special rules about calculating day intervals. The INTCK function in SAS can calculate the difference between any two dates or datetime values, and return whatever interval you're looking for (days, minutes, hours, weeks, months).

#Calculate dates subtract how to

You'd have to decide how to handle the case where patients were discharged the same day they were admitted. Max(date_2) - min(date_1) as Length_of_stay

Blog post: Do you mind if we dance with your DATEs (or DATETIMEs)?īelow are aggregated 'best answers' to this community topicįrom dates' are stored as an integer representing numer of days relative to January 1, 1960.

Whether you need to determine the duration between two dates, add or subtract time, or calculate elapsed time, this calculator simplifies the complexities associated with date and time calculations. Use our calculators to add or subtract days or times from any date, and find out how many days, months, and years passed between any two dates.

Community article: I NTNX and INTCK Function Examples In a world driven by schedules and deadlines, the Calculator for Date and Time becomes an essential tool for managing time-related calculations.

Book: SAS Functions by Example, Second Edition.Paper: The Essentials of SAS Dates and Times.