We did (briefly) look at http://chaperon.sourceforge.net/ to do
something similar but likewise didn't get very far (due to time)...

Matthew

> -----Original Message-----
> From: SRU (Search and Retrieve Via URL) Implementors
> [mailto:[log in to unmask]] On Behalf Of Mark R. Diggory
> Sent: 15 February 2006 16:05
> To: [log in to unmask]
> Subject: Re: SQL as XML
>
> Mike,
>
> Is your CQL parser Antlr or JavaCC based at all? I've been
> experimenting with using these lexical parsers to build
> parser with other query languages but without significant
> success. I'm thinking an alternative here is to use Antlr or
> JavaCC, to build a parser generation "framework". Then cases
> such as this can extend the parser generation with handlers
> for their implementation, the simplest example implementation
> would be A SAX event generator. Since these tools are
> specifically designed to handle query parsing and usually are
> tailored to working with BNF like syntaxes, getting from the
> CQL spec to an actual implementation could be automated.
>
> -Mark
>
> Mike Taylor wrote:
>
> Date: Wed, 15 Feb 2006 09:51:31 -0500
> From: Rafe Rosen <[log in to unmask]>
> <mailto:[log in to unmask]>
>
> Sorry, my bad, I should have been more clear,
>
> My project is implementing a CQL interface to
> our database of
> 160,000 recordings of animal sound and video.
> My task is to build a
> system that translates a CQL query entered by a
> human into an
> appropriate (and potentially complex) SQL
> select statement to be
> sent to the database. Since there is (was?) an XML-CQL
> representation, and XML is pretty pervasive, I
> figured if there was
> a similar schema defined for SQL I could to the
> transformation with
> XSLT.
>
>
>
> Oh, I see. Well, that makes sense. But --
>
>
>
> I have since been advised that the above
> strategy is a Bad Idea.
>
>
>
> I'd have to agree. I think it would be going too far around the
> houses, and that you'll need the idiomatic power of a Proper
> Programming Language to do the job well, rather than the
>
> super-powerful-in-the-right-context-but-unwieldy-otherwise wonder that
> is XSLT.
>
>
>
> I'm probably going to use the parse tree
> structures created by
> CQL-java (for CQL) and either ZQL or hibernate
> (for SQL).
>
>
>
> That sounds like a more promising approach.
>
>
>
> If anyone on the list has experience
> translating CQL to SQL, I would
> love to hear about it.
>
>
>
> Part of the trick is translating from abstract CQL indexes to
> correponding SQL columns. Another issue is that often
> you need to
> make joins in the SQL that don't directly correspond to
> anything in
> the CQL. It's one of those jobs that's fraught with
> many tiny issues
> that you can't see coming until you trip over them.
>
> Good luck :-)
>
>
>
> And what is the exact status of XCQL? I'm
> pretty new on this list
> and hadn't heard it had been dropped.
>
>
>
> At one stage, it was possible (in SRW, and perhaps in
> SRU though it
> would have been terrifyingly ugly) to submit the query
> in XCQL instead
> of CQL. That facility has now been withdrawn. Where
> XCQL _is_ still
> used is in echoing back the compiled query; but that
> doesn't help you
> at all if you're a server implementor. Full details at
> http://www.loc.gov/standards/sru/
> and the linked pages.
>
> _/|_
________________________________________________________________> ___
> /o ) \/ Mike Taylor <[log in to unmask]>
> <mailto:[log in to unmask]> http://www.miketaylor.org.uk
> )_v__/\ "_Apatosaurus_ sort of looks like a pro
> wrestler when most of
> the other sauropods tend to look like
> ballerinas" -- Matt Wedel.
>
>
>