SELECT

Like SQL, SPARQL provides a SELECT query form for selecting or finding data. This section describes the SELECT form.

Syntax

[ PREFIX Clause ]
SELECT [ DISTINCT | REDUCED ] result_expressions_and_variables
[ FROM Clause ]
WHERE Clause
[ Solution Modifiers ]

The optional DISTINCT solution sequence modifier eliminates duplicate results. The REDUCED modifier permits duplicate solutions to be removed but does not guarantee that they are eliminated from the results.

AnzoGraph DB can execute multiple queries concurrently. There is no hard-wired limit on the number of queries you can run concurrently, however, you can set a limit, configured by the user_queues setting, that determines how many queries may be started before additional queries are placed in a queue.

Examples

The following simple SELECT statement queries the sample Tickit data set to return all of the predicates and objects for event100:

SELECT ?predicate ?object
FROM <http://anzograph.com/tickit>
WHERE {
  <http://anzograph.com/tickit/event100> ?predicate ?object
}
ORDER BY ?predicate

predicate                                       | object
------------------------------------------------+---------------------------------------
http://anzograph.com/tickit/catid               | http://anzograph.com/tickit/category8
http://anzograph.com/tickit/dateid              | http://anzograph.com/tickit/date2129
http://anzograph.com/tickit/eventname           | Siegfried
http://anzograph.com/tickit/starttime           | 2008-10-30T15:00:00Z
http://anzograph.com/tickit/venueid             | http://anzograph.com/tickit/venue300
http://www.w3.org/1999/02/22-rdf-syntax-ns#type | http://anzograph.com/tickit/event
6 rows

This simple SELECT statement uses the DISTINCT modifier to list each distinct event name in the Tickit data set:

SELECT DISTINCT ?name
FROM <http://anzograph.com/tickit>
WHERE {
  ?event <http://anzograph.com/tickit/eventname> ?name.
}

name
-----------------------------
Adriana Lecouvreur
Eugene Onegin
La Cenerentola (Cinderella)
A Chorus Line
Hairspray
Le Reve
Hedda Gabler
Endgame
Othello
Miss Julie
...
576 rows

This example queries the sample Tickit data set to select the top 10 listings where the price per ticket is greater than $500.00:

SELECT ?listing ?priceperticket
FROM <http://anzograph.com/tickit>
WHERE {
  ?listing <http://anzograph.com/tickit/listtime> ?listtime .
  ?listing <http://anzograph.com/tickit/priceperticket> ?priceperticket .
  FILTER(?priceperticket > 500.00)
}
ORDER BY desc(?priceperticket)
LIMIT 10

listing                                   | priceperticket
------------------------------------------+----------------
http://anzograph.com/tickit/listing227412 |           2500
http://anzograph.com/tickit/listing222840 |           2500
http://anzograph.com/tickit/listing225362 |           2500
http://anzograph.com/tickit/listing214995 |           2500
http://anzograph.com/tickit/listing209658 |           2500
http://anzograph.com/tickit/listing211035 |           2500
http://anzograph.com/tickit/listing213613 |           2500
http://anzograph.com/tickit/listing215156 |           2500
http://anzograph.com/tickit/listing210898 |           2500
http://anzograph.com/tickit/listing224389 |           2500
10 rows