Posted by Gert-Jan Strik on 06/10/07 16:42

[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.

For more details, check out
http://groups.google.nl/group/microsoft.public.sqlserver.programming/browse_thread/thread/b7d0e057887380ca/0c1ff6c9523c19f0
(url may wrap)

Gert-Jan

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