Re: Has E/R had a negative impact on db?

mAsterdam wrote:
> Jan Hidders wrote:
> [snip]
>
> > Encapsulation is a nonsensical concept in the context of data
> > modelling.
>
> Yes. Yet, it is a very useful concept in partitioning software.
> It takes some time for software developers to take off that hat
> and get into the data-centric mindset needed to grow a proper
> data-model - that is /if/ they manage to do that.

Agreed. Since there is no reason to persist the same functions/methods repeatedly by keeping data and functions together all the way through CRUD functions, there is a point where these need to be decoupled. The functions defined for a given object are metadata (functions defined for a domain).

Since we often define the same metadata / functions in apps and dbms's, we will continue to have those who specify the functions from "each side" think their functions are the ones that need to stay packaged with the data, with no obvious way to get the db specs into the code or the OO methods into the dbms metadata.

> Some can't, and
> rely on hibernate or other Object-Relational-Mapping tools
> (unfortunately also abbreviated as ORM,

yes, that has confused me more than once

> _at_#&$#!)

don't forget -- I can read some Dutch

> to create
> throw-away software.
>
> > It looks a bit as if the problem is more that you are
> > retro-fitting terminology from the world of object-oriented programming
> > into the world of datamodelling that has no place there. ;-)

But you do have operations defined on domains in the dbms schema and these are tied to attributes. So, we might use other terminology when discussing the dbms, but there is some similarity, with the OO side of the house often providing more precision in the validations (in setters) and more of the functions specific to this domain (dbms domains are often specified as varchar with more detailed validations in the code to verify that a string is a valid e-mail address, for example).

> >More to
> > the point: it's certainly not an inherent part of modelling with ER
> > dialects.

Typing is, however. Cheers! --dawn Received on Tue Apr 25 2006 - 03:49:01 CEST