DateAdd Function

Format

i = dateadd(start_date, periodʃ, period_typeʅ);

Description

The dateadd function calculates a new date by adding a period to a starting date. The numeric expression start_date must be in YYYYMMDD (year/month/day) format. If no year is present, then the current or previous year is assumed in order satisfy the condition that the date is not in the future (based on the computer's system clock). The numeric expression period is the amount of time that is added to the starting date, and defaults to days. Alternatively, an optional string expression, period_type, modifies the period, and can be one of the following values:

period_type	Description
"d"	days (default)
"w"	weeks
"m"	months
"y"	years

If the period is not an integer, the period will be modified and the calculation will use days. For example, the following calculations are identical:

dateadd(20200319, 1.5, "y");
dateadd(20200319, 1.5 * 365.25, "d");

Return Value

The function returns a date calculated by adding the period to the starting date. If the starting date cannot be processed, the function returns default.

Examples

dateadd(20121225, 7); // returns 20130101

dateadd(20120228, 1); // returns 20120229
dateadd(20130228, 1); // returns 20130301

dateadd(20040820, 3, "w"); // returns 20040910
dateadd(20040820, 3, "m"); // returns 20041120
dateadd(20040820, 3, "y"); // returns 20070820

dateadd(20001010, -3, "m"); // returns 20000710