DATEs in SQL

DATEADD(): Add or subtract datetime values and the result is a date

DATEADD(DATEPART, number, date]

DATEPART: Unit of measurement (DD,MM etc) number: An integer value to add or subtract date: A datetime value

-- Return the DeliveryDate as 5 days after the ShipDate
SELECT OrderDate, 
       DATEADD(DD, 5, ShipDate) AS DeliveryDate
FROM Shipments

DATEDIFF(): takes the difference between two date times and returns a number

DATEDIFF(datepart , startdate, enddate)

datepart: Unit of measurement (DD,MM etc) startdate: The start date value enddate:The end date value

SELECT OrderDate, ShipDate, 
       DATEDIFF(DD, OrderDate, ShipDate) AS Duration
FROM Shipments