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From:Baron Schwartz Date:June 19 2007 3:41pm
Subject:Re: Storing a linked list
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Celko also discusses them in SQL For Smarties.

Baron

Peter Brawley wrote:
> Matt
> 
>  >I'd like to store paths to specific destinations...
> 
> See
> -- Tropashko's 'materialized modell' eg 
> http://www.dbazine.com/oracle/or-articles/tropashko4
> -- the airports example at 
> http://www.artfulsoftware.com/mysqlbook/sampler/mysqled1ch20.html
> 
> PB
> 
> -----
> 
> Matt Juszczak wrote:
>> Hi all,
>>
>> I've got a table such as the following:
>>
>> id1 char
>> id2 char
>>
>> sample data looks like this:
>>
>> id1    id2
>> 1    3
>> 2    4
>> 3    5
>> 5    6
>> 6    8
>>
>> And of course another table has something like:
>>
>> id    info1    info2    info3
>> 1    blah    blah    blah
>> 2    blah    blah    blah
>>
>> I'd like to store paths to specific destinations...
>>
>> In other words, the path from 1 to 8 is:
>>
>> 1,3,5,6,8
>>
>> I was thinking of creating a table called relationships
>>
>> start    end    path
>> 1    8    {3,5,6}
>>
>> This would allow me to easily display the path if I know the start and 
>> end, but what it doesn't allow me to do is reuse the data.
>>
>> IE: say that I calculate the path from 1 to 8 as 1,3,5,6,8, and then I 
>> want to know the path from 3 to 6.  even though this is already 
>> calculated, I have to recalculate it as another row... hence
>>
>> start    end    path
>> 1    8    {3,5,6}
>> 3    6    {5}
>>
>> I considered making another table, called hops, such as:
>>
>> start    end    relationshipID
>> 1    8    1
>>
>>
>> table hops:
>> relationshipID    start    end
>> 1        1    3
>> 1        3    5
>> 1        5    6
>> 1        6    8
>>
>> Then I could almost "reuse" those hops somehow.... but not sure.
>>
>> Can anyone recommend a good way to store this data?
>>
>> Thanks!
>>
>> -Matt
>>
> 

-- 
Baron Schwartz
http://www.xaprb.com/
Thread
Storing a linked listMatt Juszczak19 Jun
  • Re: Storing a linked listMogens Melander19 Jun
  • Re: Storing a linked listPeter Brawley19 Jun
    • Re: Storing a linked listBaron Schwartz19 Jun