Comments on: Random Number Generator in T-SQL

By: Mark Horninger

Mark Horninger — Fri, 28 Aug 2009 10:32:51 +0000

Thanks! this saved me some time this AM!

By: Timmy

Timmy — Wed, 12 Aug 2009 18:15:29 +0000

Excellent script! I modified it a tiny bit to accomplish something different, but the guts are all yours!

By: Weekly Link Post 97 « Rhonda Tipton’s WebLog

Weekly Link Post 97 « Rhonda Tipton’s WebLog — Mon, 08 Jun 2009 01:37:33 +0000

[...] Michelle Ufford has posted a Random Number Generator in T-SQL. [...]

By: green bay packers » Parapsychology

green bay packers » Parapsychology — Sat, 06 Jun 2009 10:14:53 +0000

[...] Random Number Generator in T-SQL : SQL Fool [...]

By: Generate a random number in SQL Server | John Sansom - SQL Server DBA in the UK

Fri, 05 Jun 2009 11:52:32 +0000

[...] authors, Michelle Ufford recently posted her method for generating a random number, in the post Random Number Generator in T-SQL. This got me thinking and I decided to do a little investigation of my own to identify what is [...]

By: Aaron Lowe

Aaron Lowe — Thu, 04 Jun 2009 20:27:39 +0000

I use the same as Adam does:

RAND(CHECKSUM(NEWID()))

I actually got it from Itzik about 5 years ago at SQLConnections in Las Vegas.

By: Adam Machanic

Adam Machanic — Thu, 04 Jun 2009 15:16:20 +0000

I don’t know about faster, but I think you’ll get better distribution and overall randomness with:

DECLARE @maxRandomValue TINYINT = 100
, @minRandomValue TINYINT = 0;

SELECT CAST(((@maxRandomValue + 1) – @minRandomValue)
* RAND(CHECKSUM(NEWID())) + @minRandomValue AS TINYINT) AS ‘randomNumber’;

By: AlexCuse

AlexCuse — Thu, 04 Jun 2009 14:09:16 +0000

This got me curious, so I did a little digging to see if there was anything a bit more production-ready and came across this (the accepted answer):

http://stackoverflow.com/questions/94906/how-do-i-return-random-numbers-as-a-column-in-sql-server-2005

By: AlexCuse

AlexCuse — Thu, 04 Jun 2009 13:56:03 +0000

Not sure how it stacks up speed wise (the answer is probably NOT WELL ) but one of my friends showed me this a while back:

CREATE VIEW RandomView
AS SELECT RAND() AS Val;

CREATE FUNCTION RandomFloat(@MinValue INT, @MaxValue INT)
RETURNS FLOAT AS
BEGIN
RETURN (SELECT ((@MaxValue – @MinValue) * Val) + @MinValue FROM RandomView);
END

Casting it to an int would be trivial. What I like about this is that unlike the builtin RAND() method it will return a different value for each row in the set.

select top 5 ROW_NUMBER() over (order by TABLE_NAME) blah
, dbo.RandomFloat(15, 100) random_works
, RAND() random_builtin
from INFORMATION_SCHEMA.TABLES

Kind of a stupid coding trick, but I find myself using something like this once in a while.