Re: Modeling question...
Date: Fri, 25 Jul 2008 16:33:26 +0200
> On Jul 25, 3:05 pm, Volker Hetzer <firstname.lastn..._at_ieee.org> wrote:
>> Bob Badour schrieb:
>>>>> Ooooh! Reinventing EAV with levels...
>>>> Possibly. I had a look at
>>>> http://ycmi.med.yale.edu/nadkarni/eav_CR_contents.htmand didn't find
>>>> anything exciting.
>>>> All my attributes (key value pairs) are (for the purpose of this
>>>> discussion) strings, so the Data tables hierarchy ends with
>>>> EAV_Objects in the first image of that link.
>>>> My problem is that, that I haveTest three different "Objects_1"
>>>> tables and I'd like to avoid having to replicate the EAV_Objects-Table
>>>> for each "Objects_1"-Table.
>>>> OTOH, I could have the "level" entities all be children of an id table
>>>> put the key value pairs into a child of that table. I need to try this
>>>> Thanks for providing the pointer!
>>> Just to be clear, I was more than offering a pointer. I was also
>>> ridiculing the idea of EAV.
>> I got that. :-)
>> But "we want to be able to create and delete attributes" is a customer
>> requirement. I think it's different from "I am too lazy to do a proper data
>> model". There are plenty of "normal" attributes left to model ERD like.
>> Lots of Greetings!
>> For email replies, please substitute the obvious.
> What's wrong with drop/add column?
All the things that are wrong if an application requires DDL during its normal state. No undo, no scalability, limits on the number of attributes, limits on the structure of the attribute names, the same attributes in each project/pcb/etc. and so on.
Sorry, but in my opinion DDL is for installation and maintenance. End users shouldn't trigger DDL neither directly nor indirectly.
Lots of Greetings!
-- For email replies, please substitute the obvious.Received on Fri Jul 25 2008 - 16:33:26 CEST