You know, we're taking a similar approach with XQuery right now.

CQL --> XCQL --> XSLT transform --> XQuery against XQuery source (SQL 
DB, Native XML db etc)

I fail to see the issue (though I havn't listed into the entire thread). 
I don't think the approach is a bad idea, allot of implementors will 
need to tailor an implementation to Legacy systems, I think that the SRU 
folks are not the proper location to discuss implementation details. 
Zing seems a better place if your going with that technology.

We're using the following implementation of CQL/XCQL to get to XML which 
we can use for processing/parsing queries.

http://zing.z3950.org/cql/java/

Cheers,
Mark

Rafe Rosen wrote:

> 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.
>
> I have since been advised that the above strategy is a Bad Idea.  I'm 
> probably going to use the parse tree structures created by CQL-java 
> (for CQL) and either ZQL or hibernate (for SQL).
>
> If anyone on the list has experience translating CQL to SQL, I would 
> love to hear about it.  And what is the exact status of XCQL?  I'm 
> pretty new on this list and hadn't heard it had been dropped.
>
> Thanks much!
>
> Rafe Rosen
> Software Developer / System Administrator
> Macaulay Library
> Cornell Lab of Ornithology
> Ithaca, NY 14850
> 607 254 2132
>
> On Wed, 15 Feb 2006, Mike Taylor wrote:
>
>>> Date: Mon, 13 Feb 2006 16:32:28 -0500
>>> From: Rafe Rosen <[log in to unmask]>
>>>
>>> Hey all- for a new search tool I'm writing, I'm thinking it might be
>>> prudent to use XML transformations to convert between some various
>>> query formats.  Is anyone out there aware of an XML schema that
>>> could represent a SQL select statement?
>>
>>
>> Sorry, I think you're on the wrong mailing list :-)  In SRU, we don't
>> use SQL at all, and we recently dropped XCQL which was the only
>> XML-based query language we had.
>>
>> _/|_     
>> ___________________________________________________________________
>> /o ) \/  Mike Taylor  <[log in to unmask]>  
>> http://www.miketaylor.org.uk
>> )_v__/\  "Covenant strode pustulatingly across the gibbous room, the
>>      preternatural sun playing lambently across his gloaming features"
>>      -- Steven Donaldson, "Lord Lambent's Bane"
>>