## random integer number scalar function

 Author Message kodracon SSC Journeyman Group: General Forum Members Points: 83 Visits: 162 Comments posted to this topic are about the item random integer number scalar function Jeff Moden SSC Guru Group: General Forum Members Points: 52158 Visits: 40321 Ummm... good idea and nice try... but doesn't work to create different random numbers within the same Select. For example, using the eample Select you have with your code....`select dbo.fx_getrandomnumber(500, 300, rand())FROM dbo.TallyWHERE N <= 10`... will return 10 identical numbers. --Jeff ModenRBAR is pronounced ree-bar and is a Modenism for Row-By-Agonizing-Row.First step towards the paradigm shift of writing Set Based code: Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column.Although they tell us that they want it real bad, our primary goal is to ensure that we dont actually give it to them that way.Although change is inevitable, change for the better is not.Just because you can do something in PowerShell, doesnt mean you should. Helpful Links:How to post code problemsHow to post performance problemsForum FAQs Jeff Moden SSC Guru Group: General Forum Members Points: 52158 Visits: 40321 Here's a "fix" for your code... doesn't change a thing in the code... just the way the "seed" for the RAND function works...`select dbo.fx_getrandomnumber(500, 300, rand(CHECKSUM(NEWID())))FROM dbo.TallyWHERE N <= 10`That will randomly generate 10 "different" integers with the understanding that it's the nature of random numbers to occasionally be duplicate in any set of random numbers.If I may suggest, if you need to write that much code to use a function, you may want to consider not even using a function. Just do it "inline".` SELECT ABS(CHECKSUM(NEWID()))%(500-300+1)+300 FROM dbo.Tally WHERE N <= 10` --Jeff ModenRBAR is pronounced ree-bar and is a Modenism for Row-By-Agonizing-Row.First step towards the paradigm shift of writing Set Based code: Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column.Although they tell us that they want it real bad, our primary goal is to ensure that we dont actually give it to them that way.Although change is inevitable, change for the better is not.Just because you can do something in PowerShell, doesnt mean you should. Helpful Links:How to post code problemsHow to post performance problemsForum FAQs kodracon SSC Journeyman Group: General Forum Members Points: 83 Visits: 162 thanks thats a useful technique! ChrisM@Work SSChampion Group: General Forum Members Points: 10311 Visits: 19232 Now this is interesting. Watch what happens when you try to find out how many of those random integers are randomly repeated:`SELECT Number, COUNT(*) FROM (SELECT ABS(CHECKSUM(NEWID()))%(500-300+1)+300 AS Number FROM dbo.Numbers WHERE number <= 200) d GROUP BY Number ORDER BY Number` “Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail ShawFor 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 ModenExploring Recursive CTEs by Example Dwain Camps Jeff Moden SSC Guru Group: General Forum Members Points: 52158 Visits: 40321 That's about what I would expect from an almost real set of random numbers. --Jeff ModenRBAR is pronounced ree-bar and is a Modenism for Row-By-Agonizing-Row.First step towards the paradigm shift of writing Set Based code: Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column.Although they tell us that they want it real bad, our primary goal is to ensure that we dont actually give it to them that way.Although change is inevitable, change for the better is not.Just because you can do something in PowerShell, doesnt mean you should. Helpful Links:How to post code problemsHow to post performance problemsForum FAQs ChrisM@Work SSChampion Group: General Forum Members Points: 10311 Visits: 19232 Jeff Moden (11/28/2008)That's about what I would expect from an almost real set of random numbers.You mean almost reel, right? -- did you catch the dupes? “Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail ShawFor 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 ModenExploring Recursive CTEs by Example Dwain Camps ChrisM@Work SSChampion Group: General Forum Members Points: 10311 Visits: 19232 Jeff Moden (11/28/2008)That's about what I would expect from an almost real set of random numbers.Sorry Jeff, should have explained more:`SELECT Number, COUNT(*) as NumberCountFROM (SELECT ABS(CHECKSUM(NEWID()))%(500-300+1)+300 AS Number FROM dbo.Numbers WHERE number <= 200) d GROUP BY Number ORDER BY Number`Some results:`Number NumberCount ----------- ----------- 300 1303 1303 1305 2307 3307 3307 1309 2``SELECT Number, SUM(NumberCount), count(*)FROM (SELECT Number, COUNT(*) as NumberCount FROM (SELECT ABS(CHECKSUM(NEWID()))%(500-300+1)+300 AS Number FROM dbo.Numbers WHERE number <= 200 ) d GROUP BY Number ) d2GROUP BY NumberORDER BY Number`Some results:`Number ----------- ----------- ----------- 301 4 3304 1 1307 2 2308 1 1309 1 1` “Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail ShawFor 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 ModenExploring Recursive CTEs by Example Dwain Camps Jeff Moden SSC Guru Group: General Forum Members Points: 52158 Visits: 40321 Chris Morris (11/28/2008)Jeff Moden (11/28/2008)That's about what I would expect from an almost real set of random numbers.You mean almost reel, right? -- did you catch the dupes?Yep... and the dupes are appropriate for such a small set of random numbers. Consider the simplest of all random number systems... Black and Red spots (with the occasional Green spot or spots) on a Roulette wheel... what would you guess would be the maximum number of times that, say, Black would show up consecutively? --Jeff ModenRBAR is pronounced ree-bar and is a Modenism for Row-By-Agonizing-Row.First step towards the paradigm shift of writing Set Based code: Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column.Although they tell us that they want it real bad, our primary goal is to ensure that we dont actually give it to them that way.Although change is inevitable, change for the better is not.Just because you can do something in PowerShell, doesnt mean you should. Helpful Links:How to post code problemsHow to post performance problemsForum FAQs RBarryYoung SSChampion Group: General Forum Members Points: 10134 Visits: 9517 Yeah, but he's getting dupes, even from the Group By categories, Jeff.Chris: FWIW, I am not seeing this on my Laptop. -- RBarryYoung, (302)375-0451 blog: MovingSQL.com, Twitter: @RBarryYoungProactive Performance Solutions, Inc. "Performance is our middle name."

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