model inherited object

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?

TIA
Phil Received on Wed Jun 21 2006 - 06:25:13 CDT