Re: Is this bad design ?

... your initial question was: is this bad design? It think it is. It is redundant and error prone. If you cannot change the database schema, you must live with your design. But, if database access is encapsulated in one class/package/module in your application, it should be possible to change the database schema without too much side effects? Instead of setting still_valid to true/false you must insert(if non-existing)/delete a row in ValidMother. This may be realized as a stored procedure. I would say that adding constraints to a database schema often has impact on the application level if normalization/redundancy is an issue (thats why db access should be encapsulated).

Regards,
Fabian

ben brugman wrote:
> "Fabian Buettner" <green_at_tzi.de> wrote in message
> news:404DC817.2090804_at_tzi.de...
>

>>If only valid mothers can have children, you could partition your Mother
>>table as follows:
>>
>>Mother( mother_id primary key, etc_fields )
>>-- all mothers
>>
>>ValidMother( mother_id primary key + foreign key ref Mother(mother_id))
>>-- "valid mother" ids
>>
>>Child( mother_id foreign key ref. ValidMother(mother_id), more_fields)
>>
>>This way you can ensure that only valid mothers are referenced by
>>children. Also (if referential integrity is available), a mother can not
>>become invalid (i.e., delete entry from ValidMother) when there are
>>still children referencing it.

>
Received on Tue Mar 09 2004 - 17:36:13 CET