random integer number scalar function

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random integer number scalar function

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Jeff Moden

Posted Friday, November 28, 2008 5:53 PM

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Dang... I missed that... was looking at the wrong column for "dupes".

--Jeff Moden

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Post #610612

Jeff Moden

Posted Friday, November 28, 2008 6:22 PM

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Chris, I've created a Numbers table with the same column name as you (Number), and I cannot get the code to fail the same way as you have with the dupes and all.

What version of SQL Server do you have and are you using either QA or SMS for the interface? I've seen the Oracle version of TOAD produce such things, but never QA or SMS. Also, single or multi CPU on your box?

--Jeff Moden

Post #610613

ChrisM@Work

Posted Saturday, November 29, 2008 3:24 AM

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Jeff Moden (11/28/2008)

It doesn't happen on the 2k5 box, only on the 2k box queried from either QA or SMS. Version is 8.00.760 (SP3) and it's dual-processor.

^{“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw}

For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden
Exploring Recursive CTEs by Example Dwain Camps

Post #610664

Jeff Moden

Posted Saturday, November 29, 2008 6:59 AM

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I've not seen such a thing... perhaps try using MaxDop 1 just to see if parallelism is getting to it? I'd try it on a multi-processor box if I had access to one, but I don't so I can't hammer it out on this end. Sorry.

--Jeff Moden

Post #610693

RBarryYoung

Posted Saturday, November 29, 2008 9:04 AM

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Huhn, the bug happens on my last remaining SQL 2000 server also. MAXDOP has no effect on it.

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Post #610707

Jeff Moden

Posted Saturday, November 29, 2008 9:06 AM

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rbarryyoung (11/29/2008)

Huhn, the bug happens on my last remaining SQL 2000 server also. MAXDOP has no effect on it.

Is it a multi CPU box you're working on? Also, which SP are you guys using? I'm using sp3A... never had the hair to go to 4 because I heard about some performance issues.

--Jeff Moden

Post #610708

Jeff Moden

Posted Saturday, November 29, 2008 9:09 AM

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Heh... well never mind... all of the sudden, I'm getting the same bug and I only have a single CPU...

--Jeff Moden

Post #610709

Jeff Moden

Posted Saturday, November 29, 2008 9:20 AM

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Isn't that strange? It's the GROUP BY loosing it's mind and it doesn't happen in 2k5. Not sure what to do about it yet.

--Jeff Moden

Post #610710

Jeff Moden

Posted Saturday, November 29, 2008 10:38 AM

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The only thing that I can figure out is that the optimizer in 2k5 resolves the sub-query before using it... the one in 2k seems to be trying to resolve it on the fly and makes mistakes because Number is indeterminate. I've never run into this problem before because I've either always put such things into a Temp table first or simply not done a Group By on the random number.

--Jeff Moden

Post #610742

jcrawf02

Posted Friday, December 12, 2008 6:38 AM

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Great timing Chris, I was just looking for something that would allow me to generate random numbers.

Jeff, based on your code for random test data, I had been playing with newid() and now I took another look at the checksum().

Question:

What I'm trying to do is show folks how to generate test data that we (corporate we) can share across state units, without revealing HIPAA protected information (member names/ids/dates of service, etc). If I do this to generate fake names and dates:

SELECT TOP 10 member.fullname,
	'member'+convert(varchar(25),abs(checksum(member.fullname))) AS testMember,
	member.dob,
	dateadd(dd,abs(checksum(member.dob))%(5-1+1) +1,member.dob) AS testDate
FROM member

can someone reverse the checksum somehow and read the correct data?

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