Re: ISSUE-3

On Mon, 23 Nov 2009, Marcelo Arenas wrote:

> Hi,
>
> I am a bit confused about what we mean by "supporting a feature" of
> DDL.  Assume that we are given a relation schema R(A, B) where A is
> the primary key of R. The list says that primary keys should be
> supported,  so should attribute A be a primary key of R(A, B) in the
> RDF representation of this database? The problem with this is that
> there is no way to enforce a key in RDF (RDFS). Are we just going to
> describe in RDF that A is a primary key without enforcing it?
> What about OWL? Are we planning to use owl:FunctionalProperty to
> indicate that A is a primary key? Thanks!
>

Yes, obviously a good point, from a techncial aspect we can as a WG 
depend on any other W3C Specifications (OWL) easily, and it is IMHO
*better* to re-use other identifiers instead of making up new ones, as 
long as the semantics of the identifier (and remember, *most* of the 
formal semantics of RDF(S) is not that constrained, while much more so for 
OWL) is respected.

But I'd like to see what all the other RDB2RDF tools do in this regard.

>
> All the best,
>
> Marcelo
>
> 2009/11/18 Ezzat, Ahmed <Ahmed.Ezzat@hp.com>
>>
>>
>> Hi Juan,
>>
>> You can approach this problem from different angles. Request: on the discussion page as an example:
>>
>> Tables item:
>>
>> Create Table
>> Must be supported
>>
>>
>> Let me suggest one of two formats: you can list for the Table bullet: create table, delete table, alter table, describe table or just list the ones you want to support?  I see as an example Describe table is the obvious one as a must.
>>
>> In either scenario you want to adopt, please have next to any DDL statement you want a justification, i.e., scenario(s) justifying its use?
>> Thanks,
>>
>> Ahmed
>>
>> Ahmed K. Ezzat, Ph.D.
>> HP Fellow, Business Intelligence Software Division
>> Hewlett-Packard Corporation
>> 11000 Wolf Road, Bldg 42 Upper, MS 4502, Cupertino, CA 95014-0691
>> Office:      Email: Ahmed.Ezzat@hp.com Off: 408-447-6380  Fax: 1408796-5427  Cell: 408-504-2603
>> Personal: Email: AhmedEzzat@aol.com Tel: 408-253-5062  Fax:  408-253-6271
>> From: Juan Sequeda [mailto:juanfederico@gmail.com]
>> Sent: Wednesday, November 18, 2009 7:00 AM
>> To: Sören Auer
>> Cc: Michael Hausenblas; Harry Halpin; RDB2RDF WG; Ezzat, Ahmed
>> Subject: Re: ISSUE-3
>>
>> On Tue, Nov 17, 2009 at 3:32 PM, Sören Auer <auer@informatik.uni-leipzig.de> wrote:
>> Michael Hausenblas wrote:
>> Though I see your point, DDL is the most general form of what we are talking
>> about, here, covering data model elements
>>
>> I actually think DDL is not a very general form, but rather a very specific language for creating and manipulating relational schema objects.
>>
>>
>> IMO, we should stick to the specifics. Hence, using DDL should be appropriate.
>>
>>
>> (for sure DROP, ALTER is not in
>> scope, but this is a no-brainer, I guess ;)
>>
>> Ok, but DDLs consist *only* of such statements, cf. e.g.:
>>
>> http://dev.mysql.com/doc/refman/5.1/en/sql-syntax-data-definition.html
>>
>>
>> What is missing from that list, that we should take in account?
>>
>> I'm fine with DDL and think we have used it in the discussion throughout as
>> such ...
>>
>> We can use the term DDL if everybody in the group got used to it, but from a conceptual point of view I think this is wrong and in order to avoid confusion with the outside world we should rather talk about /data model elements/ or /schema objects/.
>>
>> I think we can combine the two in this list that we are going to make. But we should also be on the same page. I see that you have Foreign Key, Integrity Constraints and Referential Integrity separate. Why? Aren't referential constraints a subset of integrity constraints. And a foreign key is a referential constraints. Those shouldn't be separate, but express them as subclasses.
>>
>> Sören
>>
>>
>