Re: Attribute-values in separate table

From: David Cressey <>
Date: Fri, 31 Aug 2007 13:09:17 GMT
Message-ID: <1qUBi.1$tY2.0_at_trndny01>

<> wrote in message
> > Why not just have a "HasLock" relation with the id's of the furniture
> > with locks? And a "HasWheels" relation with the id's of the furniture
> > with wheels?- Tekst uit oorspronkelijk bericht niet weergeven -
> Your solution creates a lot of similar tables, whereas mine groups all
> those tables into one.
> Creation of new attributes on the fly is done adding a record in my
> solution and creating a new table in yours.
> So my opinion is that my solution is preferable.
> But I'm open to all remarks!
There are two schools of thought as to whether the addition of a new attribute should or should not require additional data definition.

Adding a row to a table is data manipulation. altering a table to add a new column is data definition. Creating a new table is likewise data definition.

I'm of the school of thought that data in a database is managed better when the right to create and alter data definitions is severely restricted, while the right to manipulate data is extended to the applications that interact with the database.

The other school of thought is that the superior flexibility of defining new attributes without altering any database definitions overrules the data management advantages in prohibiting the same. I can't defend this school of thought (apparently yours) because, in my view, it leads inexorably to undocumented and therefore unusable data.

Hope this helps. Received on Fri Aug 31 2007 - 15:09:17 CEST

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