RE: SQL RAND function question

["Wilt, Charles" <WiltC@xxxxxxxxxx>]

Elvis,

I'm using a seed so that as I rerun the thing, I get the same results...

Using INT(rand() * 12), gives me a better distribution, except for the fact that I get 6 values of 12,
when I only want 0-11.

As I said in my other post 11.99999 seemed to give me what I needed.

Charles Wilt 
Software Engineer
CINTAS Corporation - IT 92B
513.701.1307

wiltc@xxxxxxxxxx


> -----Original Message-----
> From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-
> bounces@xxxxxxxxxxxx] On Behalf Of Elvis Budimlic
> Sent: Tuesday, February 12, 2008 1:50 PM
> To: 'Midrange Systems Technical Discussion'
> Subject: RE: SQL RAND function question
>
> I don't see anything wrong that jumps out at me, so I'll ask some
> questions.
>
> Why are you using a seed value?
> What are you counting and does the sum of individual counts add up to the
> total count?
>
> I might rewrite that line as:
>
> myDate = date('2008-03-01')   + INT(rand() * 12)  months
>
> but I don't think that'll have any effect on the counts you're seeing.
>
> Elvis
>
> Celebrating 11-Years of SQL Performance Excellence on IBM i5/OS and OS/400
> www.centerfieldtechnology.com
>
>
> -----Original Message-----
> Subject: SQL RAND function question
>
> All,
>
> I'm attempting to use SQL's RAND() function to randomly assign a number
> from
> 0-11.  Actually, the 0-11
> is used as a number of months to add to 2008-03-01.
>
> Looking at a count of the results however seems to indicate I'm doing
> something wrong:
>
> Date                       count(*)
>
> 2008-03-01              13,234
> 2008-04-01               6,536
> 2008-05-01              13,262
> 2008-06-01              13,153
> 2008-07-01              13,474
> 2008-08-01              13,448
> 2008-09-01              13,245
> 2008-10-01              13,329
> 2008-11-01              13,358
> 2008-12-01              13,307
> 2009-01-01              13,542
> 2009-02-01               6,636
>
> I'm thinking perhaps the way I'm going from the RAND() results to a
> integer
> from 0-11 is the problem.
> Anybody understand what I'm doing wrong?
>
> myDate = date('2008-03-01')   + cast(round((rand(12) * 11),0) as int)
> months
>
> Thanks!
>
> Charles Wilt
>
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