SQL Server DATEADD ()

Definition and usage

The DATEADD () function adds or subtracts a specified time interval from a date.

Grammar DateAdd ( DatePart, Number, Date)

The date parameter is a valid day expression. The number is the number of intervals you want to add, and for the future time, this is positive, and for the past time, this number is negative .

The datepart parameter can be the following value:

DatePart	Abbreviations
Years	YY, yyyy
Quarter	QQ, Q
Month	MM, M
The day of the year	Dy, y
Day	DD, D
Week	WK, WW
Week	DW, W
Hours	hh
Minutes	MI, n
Seconds	SS, S
Milliseconds	Ms
Subtle	MCs
Na-Sec	Ns

Instance

Suppose we have the following "Orders" table:

OrderId	ProductName	OrderDate
1	' Computer '	2008-12-29 16:25:46.635

Now, we want to add 2 days to "OrderDate" so we can find the payment date.

We use the following SELECT statement:

SELECT OrderId, DATEADD(day,2,OrderDate)As Orderpaydatefrom Orders

Results:

OrderId	orderpaydate
1	2008-12-31 16:25:46.635

Source: >

Select top 1 ttime as StartTime from Bbstopic ORDER BY ttime Desc--endtime

SELECT DateAdd (day,-7, ' 2014/5/22 11:55:00 ') as endtime--StartTime (one week)

SELECT DateAdd (day,-1, ' 2014/5/22 11:55:00 ') as StartTime--one day

SELECT DateAdd (day,-2, ' 2014/5/22 11:55:00 ') as StartTime--two days

SELECT DateAdd (month,-1, ' 2014/5/22 11:55:00 ') as StartTime--one months

SELECT DateAdd (month,-3, ' 2014/5/22 11:55:00 ') as StartTime--three months