DATEADD in SQL Server: add or subtract days, weeks, months

DATEADD moves a date by a number of units. Negative numbers go back in time. It is how almost every “last N days” filter is written.

Syntax

DATEADD(datepart, number, date)

The date part is written as a word, not a string: day, week, month, year, hour, minute. Short forms like dd and mm also work but are harder to read.

Examples

SELECT DATEADD(day,   -30, CAST(GETDATE() AS date)) AS thirty_days_ago,
       DATEADD(week,   -1, CAST(GETDATE() AS date)) AS a_week_ago,
       DATEADD(month,   1, '2026-01-15')             AS next_month,
       DATEADD(year,   -1, CAST(GETDATE() AS date)) AS a_year_ago;

Orders from the last 30 days

SELECT order_id, order_date, total_amount
FROM Orders
WHERE order_date >= DATEADD(day, -30, CAST(GETDATE() AS date))
  AND order_date <  CAST(GETDATE() AS date)
ORDER BY total_amount DESC;

The first day of last month

SELECT DATEADD(month, -1, DATEFROMPARTS(YEAR(GETDATE()), MONTH(GETDATE()), 1)) AS start_of_last_month;

DATEADD keeps the type you give it: pass a date and you get a date, pass GETDATE() and you keep the time part.