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The SYSDATETIME date function, introduced in SQL Server 2008, returns a DATETIME2 value that contains the date and time of the computer on which the instance of SQL Server is running.  The SYSDATETIME date function have more fractional seconds precision than the GETDATE date function.  The syntax of the SYSDATETIME date function is as follows:

SYSDATETIME()

The SYSDATETIME date function is a non-deterministic function and view and expressions that reference this column cannot be indexed.

Here are a few uses of the SYSDATETIME date function:

Usage #1 : Log the Date and Time When a Row is Inserted in a Table

CREATE TABLE [dbo].[Transactions] (
    [TransactionID]        INT NOT NULL IDENTITY(1, 1) PRIMARY KEY,
    [AccountNumber]        VARCHAR(10),
    [Amount]               MONEY,
    [TransactionDate]      DATETIME DEFAULT ( SYSDATETIME() )
)


INSERT INTO [dbo].[Transactions] ( [AccountNumber], [Amount] )
VALUES ( '123-456-78', 1000.00 )

Usage #2 : Generate a Random Number

SELECT DATEPART(NS, SYSDATETIME()) / 100 AS [Random Number]

Usage #3 : Generate a Random Number Within a Range

DECLARE @MinValue     INT
DECLARE @MaxValue     INT


SET @MinValue = 51
SET @MaxValue = 100


SELECT (DATEPART(MS, SYSDATETIME()) % ( @MaxValue - @MinValue + 1)) + @MinValue AS [Random Number]

Usage #4 : Generate an Account Number, Reference Number or Tracking Number

-- Assuming [dbo].[Tracking] Table Contains All Existing Tracking Numbers
DECLARE @NewNumber        DECIMAL(10, 0)

SELECT @NewNumber = MAX([TrackingNumber]) + 1
FROM [dbo].[Tracking]
WHERE [TrackingNumber] > YEAR(SYSDATETIME()) * 1000000 + 
                         MONTH(SYSDATETIME()) * 10000 + 
                         DAY(SYSDATETIME()) * 100


IF @NewNumber IS NULL
    SET @NewNumber = YEAR(SYSDATETIME()) * 1000000 + 
                     MONTH(SYSDATETIME()) * 10000 + 
                     DAY(SYSDATETIME()) * 100 + 1

Usage #5 : Use as a Seed in the RAND Function

SELECT RAND(DATEPART(NS, SYSDATETIME()))

Usage #6 : Return a Random Number of Records

SELECT TOP (DATEPART(MS, SYSDATETIME())) *
FROM [master].[dbo].[spt_values]
ORDER BY NEWID()

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