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Your first SPARQL query

The simplest possible query

Here is a very simple SPARQL query:

$ sparql --data ../social.ttl --query simple.sparql

query:

SELECT ?person
WHERE {
    <http://elmonline.ca/luke> <http://xmlns.com/foaf/0.1/knows> ?person .
}

results:

----------------------------------------------------------
| person                                                 |
==========================================================
| <http://www.linkedin.com/pub/matthew-links/44/381/647> |
| <http://www.linkedin.com/pub/mark-wilkinson/1/674/665> |
| <http://www.linkedin.com/in/mcourtot>                  |
----------------------------------------------------------

Prefixes

We can add URI prefixes to make the query easier to read:

$ sparql --data ../social.ttl --query prefix.sparql

query:

PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?person
WHERE {
    <http://elmonline.ca/luke> foaf:knows ?person .
}

results:

----------------------------------------------------------
| person                                                 |
==========================================================
| <http://www.linkedin.com/pub/matthew-links/44/381/647> |
| <http://www.linkedin.com/pub/mark-wilkinson/1/674/665> |
| <http://www.linkedin.com/in/mcourtot>                  |
----------------------------------------------------------

But how did we know what URIs to use in our query?

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