Re: SQL, related records (quotes)

From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Fri, 24 Jun 2005 23:31:19 +0200
Message-ID: <42bc7ba9$0$38464$e4fe514c_at_news.xs4all.nl>

Jan Hidders wrote:

> Stefan Rybacki wrote:
> 

>> timpea_at_gmail.com wrote:
>>
>>> Hi,
>>>
>>> I have a website that users can request quotes, and a user may also
>>> make a new quote that links to a previous quote.
>>>
>>> QuoteNo PreviousQuoteNo
>>> 1
>>> 2
>>> 3 1
>>> 4 3
>>> 5 4
>>>
>>> If i request quoteNo 3 i want to have a list of all the related quotes.
>>>
>>>
>>> RelQuote
>>> 1
>>> 3
>>> 4
>>> 5
>>>
>>> Is this possible with a SQL statement? or would i be best doing a loop
>>> in asp and many requests?
>>> Thanks Tim Pearson
>>>
>>
>> Try the nested sets model.
>
> Are you sure the relation describes always a tree?

Values like
QuoteNo PreviousQuoteNo

       3           6
       6           3

or just
QuoteNo PreviousQuoteNo

       3 3

are possible, so no tree. The columnnames suggest the OP does not want this to happen. They don't help to prevent these loops though. Received on Fri Jun 24 2005 - 23:31:19 CEST