SQL Server DATEADD() Function

Add one year to a date, then return the date:

SELECT DATEADD(year, 1, '2017/08/25') AS DateAdd;

Definition and Usage

The DATEADD() function adds a time/date interval to a date and then returns the date.

DATEADD( interval, number, date)

Parameter	Description
interval	Required. The time/date interval to add. Can be one of the following values: year, yyyy, yy = Year quarter, qq, q = Quarter month, mm, m = month dayofyear, dy, y = Day of the year day, dd, d = Day week, ww, wk = Week weekday, dw, w = Weekday hour, hh = hour minute, mi, n = Minute second, ss, s = Second millisecond, ms = Millisecond
number	Required. The number of interval to add to date. Can be positive (to get dates in the future) or negative (to get dates in the past)
date	Required. The date that will be modified

Works in:	SQL Server (starting with 2008), Azure SQL Database, Azure SQL Data Warehouse, Parallel Data Warehouse

Add two months to a date, then return the date:

SELECT DATEADD(month, 2, '2017/08/25') AS DateAdd;

Subtract two months from a date, then return the date:

SELECT DATEADD(month, -2, '2017/08/25') AS DateAdd;

Add 18 years to the date in the BirthDate column, then return the date:

SELECT LastName, BirthDate, DATEADD(year, 18, BirthDate) AS DateAdd FROM Employees;