deja_at_2bytes.co.uk wrote:
> hi bob,
>
>
>>post is a crank. That said, I suggest the first step toward a solution
>>might be to avoid the First Great Blunder.
>
>
> I have just started reading about First Great Blunder ie class = table,
> row = object is wrong, which is obviously my design. Though I am
> somewhat restricted by the current solution, being new to this whole
> "Blunder" thing - any pointers on how it would be best to model this
> scenario avoiding this blunder.
See my earlier comment regarding cranks. To my knowledge, I am not one
of those. Although, I am allegedly a fraud of ambiguous rank.
I can offer some pointers to pointers, though. I would suggest Fabian
Pascal's _Practical Issues in Database Management_ book and
Date/Darwen/Lorentzos' _Temporal Data and the Relational Model_.
I will warn you that SQL doesn't really support the
Date/Darwen/Lorentzos proposals for dealing with temporal data, though.
> Bob Badour wrote:
>
>>deja_at_2bytes.co.uk wrote:
>>
>>
>>>sorry - crossposting (from sqlserver programming) as it's more likely
>>>to be relevant here
>>>
>>>I have a table which I have previously used for objects of a certain
>>>class i.e.
>>>
>>>book
>>>
>>>this table has a number of columns representing the properties of the
>>>book i.e number of pages, author etc.
>>>
>>>I want to be able to record an inherited object so for example I will
>>>have Book1_v1 and Book1_v2 - the only difference between them being the
>>>number of pages and the title. However Book1_v3 might be inherited from
>>>Book1_v2 but with a different title only while Book1_v4 might be the
>>>same as Book1_v3 but with a different publication date.
>>>
>>>If I copy the Book1_v1 to a new record for Book1_v2 and change the
>>>number of pages, if I then change the author of Book1_v1, it will not
>>>be reflected in Book1_v2 (and it would be difficult to do via triggers
>>>because you cannot be certain which fields are "overridden").
>>>
>>>Even if I have a table that says [BookId, version number, property,
>>>value] to override any number of properties then I am still going to
>>>end up with horrible joins and datatype issues and working my way back
>>>from v4 to v1 to get a complete row would be a nightmare.
>>>
>>>What is the solution?
>>
>>Anyone who tells you they have a solution based on a sketchy newgroup
>>post is a crank. That said, I suggest the first step toward a solution
>>might be to avoid the First Great Blunder.
>
>
Received on Wed Jun 21 2006 - 16:30:22 CDT
