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Posted by Hugo Kornelis on 06/10/07 23:00
On Sun, 10 Jun 2007 18:42:28 +0200, Gert-Jan Strik wrote:
>[snip]
>> >>checksum(newid()) is better than the rand() function.
>> >
>> > Hi Erland,
>> >
>> > What exactly makes checksum(newid()) better than rand() ?
>>
>> Here is a practical reason:
>>
>> select rand(), checksum(newid())
>> from (select n = 1 union all select 2 union all select 4) as x
>>
>> I believe that there also issues with the randomness of rand(), although
>> I don't remember the exact details. Steve Kass knows the full story.
>
>The rand() function is not random at all. It will give the next number
>in from a repeatable sequence of numbers, based on the seed.
Hi Gert-Jan,
Isn't that what all random number generators do?
And isn't newid() more or less the same (using a different seed and a
different algorithm to compute the next value, but still computing some
formula with a seed as input to get at a pseudo-random value?)
--
Hugo Kornelis, SQL Server MVP
My SQL Server blog: http://sqlblog.com/blogs/hugo_kornelis
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