Find all TAP services; return their accessURLs
----------------------------------------------

::

  SELECT ivoid, url 
  FROM rr.capability 
    NATURAL JOIN rr.accessurl 
  WHERE standard_id='ivo://ivoa.net/std/TAP'

Find all SIA services that might have spiral galaxies 
-----------------------------------------------------

This is a tricky one; a keyword query here obviously doesn't help much;
still, it's the closest we can get with what's available in the registry
alone.  Also note that we should have an IR-type text match here; we
probably can require a has_word function on registry servers rather than
use the LIKE-hack below::

  SELECT ivoid, url 
  FROM rr.capability 
    NATURAL JOIN rr.resource
    NATURAL JOIN rr.accessurl 
  WHERE standard_id='ivo://ivoa.net/std/SIA'
    AND (
      subject LIKE '%spiral%'
      OR res_description LIKE '%spiral%')


Find all SIA services that provides infrared images
---------------------------------------------------

The following scheme wouldn't work for UV (since it would clash with
EUV).  We'll want to mandate a user defined function ivo_hasword (or
similar) to make this work properly.

  SELECT ivoid, url 
  FROM rr.capability 
    NATURAL JOIN rr.resource
    NATURAL JOIN rr.accessurl 
  WHERE standard_id='ivo://ivoa.net/std/SIA'
    AND waveband LIKE '%Infrared%'


Find all searchable catalogs that provide a column containing redshift
----------------------------------------------------------------------

::

  SELECT ivoid, url 
  FROM rr.capability 
    NATURAL JOIN rr.tablecolumn
    NATURAL JOIN rr.accessurl 
  WHERE standard_id='ivo://ivoa.net/std/ConeSearch'
    AND ucd='src.redshift'


Find all the resources that are registered by some publisher
------------------------------------------------------------

This needs some clarification; if it is intended to find out what the
originating registry is, I'd say that's futile since registries mirror
their entries.

Finding out what records come from a given authority, that's easy::

  SELECT ivoid 
  FROM rr.resource
  WHERE ivoid LIKE 'ivo://org.gavo.dc%'

Also easy: What registry records are there from a given publisher::

  SELECT ivoid 
  FROM rr.resource
  WHERE publisher_ivoid='ivo://ned.ipac/NED'

or::

  SELECT ivoid 
  FROM rr.resource
  WHERE publisher_name LIKE '%gavo%'

Finding out the registry responsible for an authority currently is not
supported.  Doing cleanly would require a table managed_authority (which
is already there internally at GAVO DC, but I'd think it doesn't need to
be public.


Find all searchable registries
------------------------------

...and return the accessURLs to their search interfaces.

This assumes we have a data model id assigned::

  SELECT url 
  FROM rr.capability_detail 
    NATURAL JOIN rr.capability 
    NATURAL JOIN rr.accessurl 
  WHERE detail_utype='Resource.capability.dataModel.ivoId' 
    AND detail_value='ivo://ivoa.net/std/RegistryModel-1.0'


Find all resources of a particular type
---------------------------------------

::

  SELECT *
  FROM rr.resource
  WHERE resource_type='vstd:Standard'


Return the resource having a particular identifier
--------------------------------------------------

If "resource" means "the complete resource record" here, that doesn't
work right now.  You'd have to go through OAI-PMH (which I consider
fair, btw.).


Find all TAP services exposing a table...
-----------------------------------------

...having some word in the description and a column with a given UCD::

  SELECT ivoid, url, name, ucd, description
  FROM rr.capability 
    NATURAL JOIN rr.accessurl
    NATURAL JOIN rr.tablecolumn
    NATURAL JOIN rr.rsctable
  WHERE standard_id='ivo://ivoa.net/std/TAP'
    AND table_description like '%uasar%'
    AND ucd='phot.mag;em.opt.V'


Find all SSAP services that provide time series, not spectra
------------------------------------------------------------

How do you tell, from VOResource?


Find all SSAP services that provide theoretical spectra, not observational ones
-------------------------------------------------------------------------------

::

  SELECT url 
  FROM rr.capability_detail 
    NATURAL JOIN rr.capability 
    NATURAL JOIN rr.accessurl 
  WHERE detail_utype='Resource.capability.dataSource' 
    AND standard_id='ivo://ivoa.net/std/SSA'
    AND detail_value='theory'


Find all services of any type that provide galaxy spectra, not stellar ones
---------------------------------------------------------------------------

See above, `Find all SIA services that might have spiral galaxies`_


Find all ConeSearch services that provide stellar distance information
----------------------------------------------------------------------

::

  SELECT url, name, ucd, description
  FROM rr.capability 
    NATURAL JOIN rr.accessurl
    NATURAL JOIN rr.tablecolumn
  WHERE standard_id='ivo://ivoa.net/std/ConeSearch'
    AND ucd like 'pos.parallax%'  

(ok, that would not only catch stellar, but that's again an issue of
proper keywords).


Find all services that provide theoretical isochrones
-----------------------------------------------------

How do you tell, from VOResource?


The service at X is down, who do I call?
----------------------------------------

::

  SELECT contact_email 
  FROM rr.resource 
    NATURAL JOIN rr.accessurl 
  WHERE url LIKE 'http://datanet.csiro.au:80/astrogrid-registry/%';