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| vickas |
 Posted: Wed Oct 23, 2013 10:56 pm Post subject: Generating Unique random number(INteger - 6 digits) |
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Centurion
Joined: 18 Aug 2013
Posts: 126
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I need to generate a unique random number (must be a integer of only 6 digits )
I used RAND() function , but its generating decimal number.
Is there any other esql numeric function to generate unique random numbers ? If not , how to generate a integer(6 digits) using RAND() ? |
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| dogorsy |
| Posted: Wed Oct 23, 2013 11:19 pm Post subject: |
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Knight
Joined: 13 Mar 2013
Posts: 553
Location: Home Office
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| Quote: |
| how to generate a integer(6 digits) using RAND() ? |
What does the documentation say ?... RAND generates a number between 0.0 and 1.0
| Quote: |
| Is there any other esql numeric function to generate unique random numbers ? |
Have you learned mathematics at school ? in particular MULTIPLICATION ?
RAND() {the correct maths operation here } and multiplier with the correct number of zeros...
Before asking basic questions you need:
1- read the documentation
2- think about the problem you want to solve and try to find a solution yourself. |
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| smdavies99 |
| Posted: Wed Oct 23, 2013 11:21 pm Post subject: |
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Jedi Council
Joined: 10 Feb 2003
Posts: 6076
Location: Somewhere over the Rainbow this side of Never-never land.
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If the random number is between say 0.0001 and 0.99999 then
Multiply it by the number of digits you need so for 6 digits it is 1,000,000
Then cast to integer or use another method to drop the mantissa.
For a bit more randomness get another random number preferably with a different seed and multiply the second part by 1,000 and OR the results.
Not that hard really.
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| gs |
| Posted: Wed Oct 23, 2013 11:26 pm Post subject: |
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Master
Joined: 31 May 2007
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| dogorsy |
| Posted: Wed Oct 23, 2013 11:36 pm Post subject: |
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Knight
Joined: 13 Mar 2013
Posts: 553
Location: Home Office
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Of course, there are other ways of doing it, for example, write your own function, you will need a prime number as a base and a simple algorithm.
Or you can use part of the timestamp, for example milliseconds.
you need to think what is better for you. |
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| vickas |
| Posted: Thu Oct 24, 2013 12:59 am Post subject: |
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Centurion
Joined: 18 Aug 2013
Posts: 126
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@ Dogorsy !!
I believe that am a gud math student !!
and i just wonder how kud you ask me to multiple with 10000 to my RAND result,etc ...
I was very particular of getting only 6 random digits.
RAND generated 0.001251258885 for the first time , and the second time it gave me 0.5635853144 , and if this is the case, multiplying with 1,000000 wud not give me the result with 6 digts al the time..
and I know that we can generate a 6 digit random number using current timestamp milisec,micro sec format ! |
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| smdavies99 |
| Posted: Thu Oct 24, 2013 1:06 am Post subject: |
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Jedi Council
Joined: 10 Feb 2003
Posts: 6076
Location: Somewhere over the Rainbow this side of Never-never land.
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Ok
0.001251258885 * 10exp6 = 1251.258885 drop mantissa and cast as char
= '1251'
Overlay onto '000000' gives '001251'
0.5635853144 * 10exp6 = 563585.3144 drop mantissa and cast as char = '563585'
Overlay onto '000000' gives '563585'.
You could always cast the number to a char using a relevant format clause that would include any leading zero's.(my preferred method but requires more investigation and testing to get it right)
Why don't you try a few things for yourself?
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Every time you reinvent the wheel the more square it gets (anon). If in doubt think and investigate before you ask silly questions. |
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| dogorsy |
| Posted: Thu Oct 24, 2013 2:07 am Post subject: |
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Knight
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Posts: 553
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| vickas wrote: |
@ Dogorsy !!
I believe that am a gud math student !!
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maybe you are. Have you got to the times tables yet ? what about multiplication ? |
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| joebuckeye |
| Posted: Thu Oct 24, 2013 4:38 am Post subject: |
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Partisan
Joined: 24 Aug 2007
Posts: 365
Location: Columbus, OH
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And just because you can generate a random 6 digit number doesn't mean it will all be unique either. There is no telling when you will get a previously generated number.
Which is more important? Being random or being unique? |
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| dogorsy |
| Posted: Thu Oct 24, 2013 5:27 am Post subject: |
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Knight
Joined: 13 Mar 2013
Posts: 553
Location: Home Office
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| joebuckeye wrote: |
And just because you can generate a random 6 digit number doesn't mean it will all be unique either. There is no telling when you will get a previously generated number.
Which is more important? Being random or being unique? |
But the OP is a "gud math student !! " so he should know that random is just that, and could be repeating ... or maybe I am misunderstanding what the OP means by "gud" |
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| kimbert |
| Posted: Thu Oct 24, 2013 6:45 am Post subject: |
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Jedi Council
Joined: 29 Jul 2003
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Location: Southampton
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| Quote: |
| maybe I am misunderstanding what the OP means |
Yes, that's possible. The OP has explained the problem. We have suggested solutions. Let's leave it there.
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| vickas |
| Posted: Fri Oct 25, 2013 1:23 am Post subject: |
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Centurion
Joined: 18 Aug 2013
Posts: 126
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@ smdavies99
This solution works fine when i send a single message(contains multiple records).
RAND() is generating the same number for the second message(contains multiple records) as well. |
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| smdavies99 |
| Posted: Fri Oct 25, 2013 1:29 am Post subject: |
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Jedi Council
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Posts: 6076
Location: Somewhere over the Rainbow this side of Never-never land.
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| vickas wrote: |
@ smdavies99
This solution works fine when i send a single message(contains multiple records).
RAND() is generating the same number for the second message(contains multiple records) as well. |
That's why you need to change the SEED every time.
http://en.wikipedia.org/wiki/Random_seed
Changing it TWICE for every output is IMHO pretty good. Remember that using six digits limits you to 999,999 different numbers.
You may have to call a java function that will allow you to change the seed.
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Every time you reinvent the wheel the more square it gets (anon). If in doubt think and investigate before you ask silly questions. |
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| fjb_saper |
| Posted: Fri Oct 25, 2013 4:55 am Post subject: |
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Grand High Poobah
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And if you really need distinct numbers not so much as random, have you considered taking the last 6 chars of BROKERUUIDASCHAR ? 
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| Esa |
| Posted: Fri Oct 25, 2013 5:06 am Post subject: |
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