Re: ISSUE-3

On Mon, Nov 23, 2009 at 10:45 PM, Ezzat, Ahmed <Ahmed.Ezzat@hp.com> wrote:

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> Thanks Juan…
>
>
>
> Tomorrow we are continuing presentations.  It might be a good idea to use
> email to exchange thoughts till we are done with the presentations next
> week.
>
Sounds good

> One observation that I have which is kind of border line is the notion of
> R2RML supporting SQL DDL statements.  I think what we mean is RDFS/OWL
> equivalence to SQL DDL statements.  In other words, we are not creating
> SQL table but rather creating a class that maps an existing SQL table to the
> RDF world, etc..
>
Yes!

> If the above makes sense, one possibility is to have a table with 3
> columns: SQL column (DDL statement): RDFS column (equivalence): OWL column
> (equivalence).  In the SQL column you would have create table, then in OWL
> the equivalent is to create a class, etc…
>
That is exactly what I was thinking of. I was just trying to figure out how
to create a table in a wiki.

>
>
Ahmed
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>
>
> *From:* Juan Sequeda [mailto:juanfederico@gmail.com]
> *Sent:* Monday, November 23, 2009 19:22
> *To:* Ezzat, Ahmed
> *Cc:* Marcelo Arenas; Sören Auer; Michael Hausenblas; Harry Halpin;
> RDB2RDF WG
> *Subject:* Re: ISSUE-3
>
>
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> I have now updated the list and added justification
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> http://www.w3.org/2001/sw/rdb2rdf/wiki/Requirements/DDLCoverage
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> I have based this on our previous work [1] and a technical report of ours
> which is a survey of different approaches that take DDL and convert it to an
> ontology [2].
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>
>
> Looking forward to a discussion about this tomorrow.
>
>
>
> [1] http://www.springerlink.com/content/mv58805364k31734/
>
> [2] ftp://ftp.cs.utexas.edu/pub/techreports/tr09-04.pdf
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>
> Juan Sequeda, Ph.D Student
> Dept. of Computer Sciences
> The University of Texas at Austin
> www.juansequeda.com
> www.semanticwebaustin.org
>
>  On Mon, Nov 23, 2009 at 6:09 PM, Juan Sequeda <juanfederico@gmail.com>
> wrote:
>
> I'm sure we will all have different points of views and opinions on this.
>
>
>
> For example, the way we have done this (and we have shown this in our dexa
> paper [1]): We have mapped the create table to classes, except if the tables
> are binary relations, then they would map to object properties. How do we
> automatically do this? Reading the data dictionary or using describe
> operation.
>
>
>
> I apologize for being a bit behind on this but I've been under the weather.
> I'm in the processing of finishing the list and I will take Ahmed's
> suggestion of writing justifications. We can then discuss this tomorrow.
>
>
>
> [1] http://www.springerlink.com/content/mv58805364k31734/
>
>
> Juan Sequeda, Ph.D Student
> Dept. of Computer Sciences
> The University of Texas at Austin
> www.juansequeda.com
>
> www.semanticwebaustin.org
>
>
>
>  On Mon, Nov 23, 2009 at 11:48 AM, Ezzat, Ahmed <Ahmed.Ezzat@hp.com>
> wrote:
>
>
>
> Here is my 2 cents:
>
> The format of the information Juan is collecting needs to be modified.  I
> do not know if Juan read his email or not?  The list he is collecting is the
> list of features that the mapping language needs to support on the SQL side,
> i.e., ability to find out the PK for a given relation R; this is doable
> using DESC (describe) operation. I asked Juan to put usage scenarios for
> each item suggested on his page.  For example, scenario where creating a
> table is needed?  I did not want to go and edit the format of the page, and
> instead asked Juan to do that. Then myself and others can edit content.
>
> There is another dimension to the mapping issue on the other side, which is
> not part of what Juan is doing, i.e., RDFS or OWL usage of the information
> you get from the RDBMS side.
>
> Ahmed
>
>
>
> -----Original Message-----
> From: Marcelo Arenas [mailto:marcelo.arenas1@gmail.com]
> Sent: Monday, November 23, 2009 07:56
> To: Ezzat, Ahmed
> Cc: Juan Sequeda; Sören Auer; Michael Hausenblas; Harry Halpin; RDB2RDF WG
> Subject: Re: ISSUE-3
>
> 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!
>
> 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
> >
> >
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