DatesADDdatepart

DatesADDdatepart is a date arithmetic function used to add or subtract a specified date part to a given date value. It is found in various data processing and database contexts and is conceptually similar to other date-add functions such as DATEADD in SQL. The function typically accepts three arguments: a date_expression, a datepart, and an amount. The date_expression is the starting date or timestamp; the datepart indicates which component to modify (for example year, quarter, month, day, hour, minute, or second); the amount is an integer that can be positive or negative to indicate addition or subtraction.

Syntax: DatesADDdatepart(date_expression, datepart, amount)

Behavior: The function computes a new date by adding the specified amount of the given datepart. For calendar-aware parts like year and month, the operation respects calendar rules, including leap years and varying month lengths. When the target part is not present (for example adding one month to January 31), the result is the last valid day of the resulting month (e.g., 2020-02-29). Time components are adjusted accordingly if the input includes time information.

Return value: The same type as input if the operation succeeds; otherwise an appropriate error or null depending on implementation. Negative amounts perform subtraction.

Examples: DatesADDdatepart('2020-01-31', 'month', 1) yields '2020-02-29'; DatesADDdatepart('2020-03-15', 'year', -1) yields '2019-03-15'.

Notes: The exact syntax and supported dateparts vary by language or platform; in SQL-like contexts, a similar function might be named differently (for example DATEADD or ADDDATE).