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Coldfusion/SQL Randomize Algorithm

Posted on 2013-11-07
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Last Modified: 2013-11-11
Hi Experts,
1)  This may not exactly be a ColdFusion question, but I am going to program it in CF v10 and you guys are very smart!  SQL Guys too!!!!

Problem:  I need to generate in a random sequence a list if all possible 4 digit numbers only using the set of digits (1,2,3,4,5)

ex: 1234, 4455, 5555, 1111.

I'm not sure how to do this best.  I could
-  generate a random 4 digit number from the set of (1,2,3,4,5).  I think I did that somewhere before in a CAPTCHA routine.  

-  Search a table to make sure I didn't pick it already.  If I did retry otherwise store the number in the next slot of the table.

But at the end, it will be like looking for a needle in a haystack when I only have a few possibilities left?


2)  FYI.  I also use SQL Server 2012 and this could be part of the solution.
-- Insert rows (Sequential number column, random column)
-  Select all rows order by random column

3)  ColdFusion guys:  How do I generate the numbers sequentially between 1111 - 5555 only using the digits 1,2,3,4,5?


Any advise?

Thanks in advance,
hefterr
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Question by:hefterr
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Expert Comment

by:_agx_
ID: 39630816
I'm not sure how this fits with your app, but if it's really only values 1111-5555 what about something like this?

1. Create a table with all possible values (~600) [TableA]
2. Query the table for the "next value". (Sort by newID() to get random order)
3. Remove the "next value" from  TableA to indicate it's used. Finally insert it into TableB

That said ... what happens when you run out of numbers in the range 1111-5555 ? ;-)

EDIT:

BTW, you could generate the initial values in SQL with a CROSS JOIN. Just be careful w/them. You could easily hose your db server by accidentally bringing back a billion rows if you're not paying attention to the CROSS JOIN.  In this case it's only about ~600 rows

DECLARE @table TABLE ( value char(1) )
INSERT INTO @table ( value ) VALUES (1),(2),(3),(4),(5)

SELECT   t1.value +''+ t2.value +''+ t3.value, t4.value AS theNumber
FROM      @table t1 
                  CROSS JOIN @table t2 
                  CROSS JOIN @table t3
                  CROSS JOIN @table t4 

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Author Comment

by:hefterr
ID: 39631119
Hi _agx_,
This is a "one shot deal".  My boss asked me to give him a list of these random number (in a spreadsheet of 1 column).  I didn't ask why - and didn't care much :).  Si I'll run this once and that will be that.

So I was thinking of just loading a test table with all the possible sequential values
Q:  Do I use NumberFormat and then use left() or mid() on each of the 4 characters to see if they only contain (1,2,3,4,5)?  This was my thinking

On each insert I'd have a random column that SQL Server can generate (I forget the type).
Then I'd just
 select mynum from testable order by randcolumn

for each result, I'd put it to a file or cut and past the result set  - whatever.

Nothing fancy.

Thoughts,
hefterr
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Accepted Solution

by:
_agx_ earned 500 total points
ID: 39631153
Not sure if you saw the edit to my last post, but...  If it's just a one shot deal, I'd use SQL.

> So I was thinking of just loading a test table with all the possible sequential values

That's what I was suggesting in step #1.  The query above should generate all the numbers w/just a few lines of SQL.  To order the results randomly, just add an ORDER BY NewID() to the query. If you want to save it to a table, just add an "INSERT INTO ..." in front of the SELECT.

Edit: Something like this


DECLARE @table TABLE ( value char(1) )
INSERT INTO @table ( value ) VALUES (1),(2),(3),(4),(5)

INSERT INTO SomeOtherTable ( RandomValue )
SELECT   t1.value +''+ t2.value +''+ t3.value +''+ t4.value AS theNumber
FROM      @table t1 
                  CROSS JOIN @table t2 
                  CROSS JOIN @table t3
                  CROSS JOIN @table t4 
ORDER BY NewID()
                                          

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Author Comment

by:hefterr
ID: 39631382
Hi _agx_
Very nice solution.  You had some syntax errors I could not resolve creating the temp table so I just created a real test table and inserted 5 rows.

You had syntax errors generating the numbers - but I did fix that:
SELECT   t1.value +''+ t2.value +''+ t3.value + '' + t4.value AS theNumber
FROM      test_12345 t1
                  CROSS JOIN test_12345 t2
                  CROSS JOIN test_12345 t3
                  CROSS JOIN test_12345 t4
    ORDER BY newid()

I created a spreadsheet with 2 columns.  All the 625 numbers sequentially and another column with a random result.

Thanks for you help!!!!
all-numbers.xls
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Author Closing Comment

by:hefterr
ID: 39631394
Thanks again.  Just curious, was my CF code idea feasible looping from all numbers from 1111 - 5555 and using NUMBERFORMAT() and LEFT() to bypass numbers that contained the digits (6,7,8,9,0)?



Here is the final SQL based on your approach:

DECLARE @table TABLE ( value char(1) )
INSERT INTO @table ( value ) VALUES (1)
INSERT INTO @table ( value ) VALUES (2)
INSERT INTO @table ( value ) VALUES (3)
INSERT INTO @table ( value ) VALUES (4)
INSERT INTO @table ( value ) VALUES (5)

SELECT   t1.value +''+ t2.value +''+ t3.value + '' + t4.value AS theNumber
FROM      @table t1
                 CROSS JOIN @table t2
                 CROSS JOIN @table t3
                 CROSS JOIN @table t4
order by newid()

hefterr
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Expert Comment

by:_agx_
ID: 39631451
> You had some syntax errors I could not resolve creating the temp table

Sorry, I had to retype the code from another screen and was trying to add the VALUES clause for 2012 on the fly. It's entirely possible I messed it up :) I tested under 2005, so I used the older syntax:

INSERT INTO SomeTable (...)
SELECT 1 UNION ALL
SELECT 2 UNION ALL
SELECT 3 ....

> , was my CF code idea feasible looping from all numbers from 1111 - 5555

Not sure .. honestly I didn't quite follow the idea. It's probably me .. my head's all stopped up with a cold :)
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Author Comment

by:hefterr
ID: 39631672
Nevermind - hope you feel better!!!  There is a bad URI going around that lasts around 10 days.  Good to be working from home!
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Expert Comment

by:_agx_
ID: 39631698
Thanks! Yes, working from home definitely keeps you more healthy in that sense ;-)
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Expert Comment

by:_agx_
ID: 39632049
I was curious about the syntax, so I ran it through sqlfiddle and the VALUES stuff worked for SQL 2012 (it wouldn't work if you're using 2005 though). Though I realized the quotes in the SELECT weren't necessary. (They were there from an earlier version when I was using INT instead of CHAR):

      SELECT   t1.value +''+ t2.value +''+ t3.value +''+ t4.value AS theNumber

So for posterity here's the final working version with table variables (at least w/SQL Server 2012 anyway :)

DECLARE @table TABLE ( value char(1) )
INSERT INTO @table ( value ) VALUES (1),(2),(3),(4),(5)


SELECT   t1.value + t2.value + t3.value + t4.value AS theNumber
FROM      @table t1
                  CROSS JOIN @table t2
                  CROSS JOIN @table t3
                  CROSS JOIN @table t4
ORDER BY NewID()
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Author Comment

by:hefterr
ID: 39632146
OK  Thanks.  I was running locally with SQL 2005 so that's part of my problem.

I also cut/pasted your FIRST SQL example and it had a syntax error :
SELECT   t1.value +''+ t2.value +''+ t3.value, t4.value AS theNumber

The others corrected it!

Thanks for closing the loop!!!!
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LVL 52

Expert Comment

by:_agx_
ID: 39632160
(Edit) Yeah, that would do it.  It was written for the version you mentioned in the OP (SQL Server 2012) but that syntax wouldn't work in 2005.  That's what I get for trying to change versions on the fly ;-)

Gah... I wish EE would notify people of edits to posts!  I saw that error shortly after posting and corrected it.
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