Re: Why not many2one with pk array type

Sandy.Pittendrigh_at_gmail.com wrote:

> I disagree. Relational design is inescapably subjective.
> Normalization rules are not rules, they are guidelines.
> No two programmers model the same complex data problem the same way.

There are subjective design decisions to be made in hierarchical models too of course, but RM has enormous and proven advantages over the hierarchical ones. I'm not necessarily endorsing your claims, but if they are true then I would look for different solutions than the one you have proposed. On the whole, developer time costs much less than the value of data integrity, data independence, guaranteed access, etc. To compromise those relational principles for the sake of faster UI development seems like a poor trade-off, especially given that the data (not necessarily the data model but certainly the data) will usually have a life and a value way beyond the application that serves it.

> Hierarchical databases have other problems, but GUI mapping is not
> among them. A program can read a hierarchy and then generate a matching
> data entry form that works, without intervention by a programmer.
> Same for data query.
>
> That is now and never will be possible with relational systems.

An RDBMS can or could expose exactly as much metadata for a GUI mapping tool as a hierarchical one can - for example through business rule constraints exposed in catalogue views. Are you claiming that there is metadata inherent in a hierarchical database that cannot be represented relationally? That would seem like a startling claim. Can you substantiate it with an example? If not, it seems that your program must have exactly the same opportunity to map a GUI from both relational and hierarchical systems.

-- 
David Portas