[ECODP-dev] SPARQL background information

Thu Mar 21 21:20:04 UTC 2013

Hi Agnieszka,

the next slides series are public courses which nicely explain Linked Data (RDF)

a) RDF: http://slidewiki.org/deck/750#tree-0-deck-750-1-view
b) SPARQL: http://slidewiki.org/deck/750#tree-750-deck-1283-8-view

you need to understand first the basics of the RDF data structures
before you start with the querying part SPARQL.
There are more chapters in the course but these cover the core of your request.

Example queries:
* find dataset graphs which contain a title that contains 'Forest' (at most 10)
  select distinct ?g ?o where { graph ?g {?s
<http://purl.org/dc/terms/title> ?o. filter regex(?o, 'Forest', 'i') }
} LIMIT 10

* find all triples ?s ?p ?o  of a dataset set
  select * from
<http://open-data.europa.eu/data/dataset/Zzsmry9sSf5q137W4cvLA> where
{?s ?p ?o} limit 1000

* find datasets which belong to the publisher ESTAT
  select distinct ?g where { graph ?g {?s
<http://purl.org/dc/terms/publisher>
<http://publications.europa.eu/resource/authority/corporate-body/ESTAT>
}} limit 10

The example queries result in answers w.r.t. our test system odp.tenforce.com

For more exploration of the data in Virtuoso you can have a look into
section 10.3 THE RDF2CKAN DATASET RDF STRUCTURE of the operations
manual.
There you find the rdf queries being executed to retrieve specific
information to transfer to CKAN. These queries can be embedded in the
above once to specify additional conditions
in your select.

kind regards,

Bert

-- 
Bert Van Nuffelen

Semantic Technologies Software Architect at TenForce
www.tenforce.be

Bert.Van.Nuffelen at tenforce.com
Office: +32 (0)16 31 48 60
Mobile:+32 479 06 24 26
skype: bert.van.nuffelen