Re: Mixing OO and DB
Date: Sat, 8 Mar 2008 10:45:40 -0800 (PST)
On 8 mar, 15:49, paul c <toledoby..._at_ac.ooyah> wrote:
> It's a relatively few programmers or wannabes who imagine they "want" an
> "oodbms". In practice many, many users are hampered by the lack of
> user-defined types in rdbms' but usually don't know it. I'd say that is
> the central problem TTM is aimed at.
A user defined relation *de facto* constitutes a custom-defined type. A derived relation necessarily constitutes a sub-type.
In RM definition mindset, a subtype can actually benefit from domain constraints that are *independent* and *additional* to the one of the supertype. In OO however any inheritance mechanism forces a constraint to be either from supertype or some predetermined supertype: that is lethal.
Another example on how RM equates freedom...
> Most people are lost in the forest (recently the TTM site started to
> same problem - unbeknownst to the authors I'm sure).
Received on Sat Mar 08 2008 - 19:45:40 CET