Random Number Generator

There are many methods to generate random number in SQL Server.

Method 1 : Generate Random Numbers (Int) between Rang

---- Create the variables for the random number generation

DECLARE @Random INT;

DECLARE @Upper INT;

DECLARE @Lower INT

---- This will create a random number between 1 and 999

SET @Lower = 1 ---- The lowest random number

SET @Upper = 999 ---- The highest random number

SELECT @Random = ROUND(((@Upper - @Lower -1) * RAND() + @Lower), 0)

SELECT @Random

Method 2 : Generate Random Float Numbers

SELECT RAND( (DATEPART(mm, GETDATE()) * 100000 )

+ (DATEPART(ss, GETDATE()) * 1000 )

+ DATEPART(ms, GETDATE()) )

Method 3 : Random Numbers Quick Scripts

---- random float from 0 up to 20 - [0, 20)

SELECT 20*RAND()

-- random float from 10 up to 30 - [10, 30)

SELECT 10 + (30-10)*RAND()

--random integer BETWEEN 0

AND 20 - [0, 20]

SELECT CONVERT(INT, (20+1)*RAND())

----random integer BETWEEN 10

AND 30 - [10, 30]

SELECT 10 + CONVERT(INT, (30-10+1)*RAND())

Method 4 : Random Numbers (Float, Int) Tables Based with Time

DECLARE @t TABLE( randnum float )

DECLARE @cnt INT; SET @cnt = 0

WHILE @cnt <=10000

BEGIN

SET @cnt = @cnt + 1

INSERT INTO @t

SELECT RAND( (DATEPART(mm, GETDATE()) * 100000 )

+ (DATEPART(ss, GETDATE()) * 1000 )

+ DATEPART(ms, GETDATE()) )

END

SELECT randnum, COUNT(*)

FROM @t

GROUP BY randnum

Method 5 : Random number on a per row basis

---- The distribution is pretty good however there are the occasional peaks.

---- If you want to change the range of values just change the 1000 to the maximum value you want.

---- Use this as the source of a report server report and chart the results to see the distribution

SELECT randomNumber, COUNT(1) countOfRandomNumber

FROM (

SELECT ABS(CAST(NEWID() AS binary(6)) %1000) + 1 randomNumber

FROM sysobjects) sample

GROUP BY randomNumber

ORDER BY randomNumber

Fonte: Pinal Dave (http://blog.SQLAuthority.com), Simon Sabin (http://sqlblogcasts.com)