This document provides an introduction to SPARQL, the query language for RDF. It describes that SPARQL was created by the RDF Data Access Working Group of the W3C and became a recommendation in 2008. It has a SQL-like syntax and allows querying RDF triples through triple patterns and basic graph patterns. Common implementations include ARQ, Virtuoso, and Sesame.

1. SPARQL
Query Language for RDF
Raji GHAWI
30/03/2010

2. Introduction to SPARQL
SPARQL =
RDF Query Language + Protocol + XML Results Format
 SPARQL has been created by the RDF Data Access
Working Group (DAWG) of the W3C.
 SPARQL is a W3C Recommendation since January 2008
 It has a familiar looking SQL-style syntax.
 Several implementations are available:
 ARQ, Virtuoso, Sesame, etc.

“SPARQL will make a huge difference”
Tim Berners-Lee, May 2006
2

3. Triple Patterns



A SPARQL query contains a set of triple patterns called a basic
graph pattern.
A triple pattern is similar to an RDF triple (subject, predicate,
object), but any component can be a variable.
We say that a basic graph pattern matches a subgraph of the RDF
data, when RDF terms from that subgraph may be substituted for
the variables.

the result of the matching is an RDF graph equivalent to the subgraph.
3

4. Turtle

Turtle is an RDF serialization


The RDF part of N3
SPARQL uses Turtle+variables as triple pattern syntax
@prefix person: <http://example/person/> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
person:A
person:A
person:B
foaf:name
foaf:mbox
foaf:name
"Alice" .
<mailto:alice@example.net> .
"Bob" .
4

5. SPARQL: Triple Pattern
@prefix person: <http://example/person/> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
person:A
person:A
person:B
foaf:name
foaf:mbox
foaf:name
"Alice" .
<mailto:alice@example.net> .
"Bob" .
PREFIX person: <http://example/person/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?name
WHERE
{ ?x
foaf:name
?name }
----------| name
|
===========
| "Bob"
|
| "Alice" |
----------5

6. SPARQL: Basic Graph Pattern
@prefix person: <http://example/person/> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
person:A
person:A
person:B
foaf:name
foaf:mbox
foaf:name
"Alice" .
<mailto:alice@example.net> .
"Bob" .
PREFIX person: <http://example/person/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?name
WHERE
{ ?person
?person
foaf:mbox
foaf:name
<mailto:alice@example.net> .
?name . }
----------| name
|
===========
| "Alice" |
----------6

7. Inference
:x
:C
rdf:type
rdfs:subClassOf
:C .
:D .
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT ?type
WHERE {
?x
rdf:type
?type .
}
-------| type |
========
| :C
|
| :D
|
-------7

8. SPARQL Query Forms
SPARQL has four query forms.
These query forms use the solutions from pattern matching to
form result sets or RDF graphs.
The query forms are:



1.
2.
3.
4.
SELECT – returns all, or a subset of, the variables bound in a query
pattern match.
CONSTRUCT – returns an RDF graph constructed by substituting
variables in a set of triple templates.
ASK – returns a boolean indicating whether a query pattern matches or
not.
DESCRIBE – returns an RDF graph that describes the resources
found.
8

9. SELECT Form of SPARQL Query

A SPARQL SELECT query consists of two parts:


SELECT clause – identifies the variables to appear in the query
results
WHERE clause – provides the basic graph pattern to match against
the data graph.
9

10. SELECT Form of SPARQL Query



The query attempts to match the triples of the graph pattern
against the RDF data model.
Matching means find a set of bindings such that the
substitution of variables for values creates a triple that is in
the set of triples making up the RDF graph.
Each matching binding of the graph pattern variables to the
model nodes becomes a query solution, and the values of the
variables named in the SELECT clause become part of the
query results.
10

11. A Dataset of RDF Triples
vCard:FN
http://somewhere/MattJones/
vCard:N
vCard:FN
http://somewhere/SarahJones/
Matt Jones
vCard:Given
Sarah Jones
vCard:N
vCard:Family
vCard:Given
vCard:FN
http://somewhere/RebeccaSmith/
vCard:Family
23
vCard:Family
vCard:Given
vCard:FN
http://somewhere/JohnSmith/
Matthew
Jones
Sarah
Becky Smith
info:age
vCard:N
Jones
info:age
Smith
Rebecca
John Smith
25
vCard:Family
vCard:N
vCard:Given
Smith
John
11

12. A Dataset of RDF Triples
Subject
Predicate
Object
<http://somewhere/MattJones/>
vCard:FN
"Matt Jones"
<http://somewhere/MattJones/>
vCard:N
_:b0
_:b0
vCard:Family
"Jones"
_:b0
vCard:Given
"Matthew"
<http://somewhere/RebeccaSmith/>
vCard:FN
"Becky Smith"
<http://somewhere/RebeccaSmith/>
vCard:N
_:b1
_:b1
vCard:Family
"Smith"
_:b1
vCard:Given
"Rebecca"
<http://somewhere/JohnSmith/>
vCard:FN
"John Smith"
<http://somewhere/JohnSmith/>
vCard:N
_:b2
_:b2
vCard:Family
"Smith"
_:b2
vCard:Given
"John"
<http://somewhere/SarahJones/>
vCard:FN
"Sarah Jones"
<http://somewhere/SarahJones/>
vCard:N
_:b3
_:b3
vCard:Family
"Jones"
_:b3
vCard:Given
"Sarah"
12

13. SELECT ?x
WHERE {
?x <http://www.w3.org/2001/vcard-rdf/3.0#FN> "John Smith"
}
<http://somewhere/MattJones/>
vCard:FN
"Matt Jones" .
<http://somewhere/MattJones/>
vCard:N
_:b0 .
_:b0
vCard:Family
"Jones" .
_:b0
vCard:Given
"Matthew" .
<http://somewhere/RebeccaSmith/>
vCard:FN
"Becky Smith" .
<http://somewhere/RebeccaSmith/>
vCard:N
_:b1 .
_:b1
vCard:Family
"Smith" .
_:b1
vCard:Given
"Rebecca" .
<http://somewhere/JohnSmith/>
vCard:FN
"John Smith" .
<http://somewhere/JohnSmith/>
vCard:N
_:b2 .
_:b2
vCard:Family
"Smith" .
_:b2
vCard:Given
"John" .
<http://somewhere/SarahJones/>
vCard:FN
"Sarah Jones" .
<http://somewhere/SarahJones/>
vCard:N
_:b3 .
_:b3
vCard:Family
"Jones" .
_:b3
vCard:Given
Q1
"Sarah" .
13

14. SELECT ?x
WHERE {
?x <http://www.w3.org/2001/vcard-rdf/3.0#FN> "John Smith"
}
Q1
--------------------------------| x
|
=================================
| <http://somewhere/JohnSmith/> |
---------------------------------
14

15. SELECT ?x ?fname
WHERE {
?x <http://www.w3.org/2001/vcard-rdf/3.0#FN> ?fname
}
<http://somewhere/MattJones/>
vCard:FN
"Matt Jones" .
<http://somewhere/MattJones/>
vCard:N
_:b0 .
_:b0
vCard:Family
"Jones" .
_:b0
vCard:Given
"Matthew" .
<http://somewhere/RebeccaSmith/>
vCard:FN
"Becky Smith" .
<http://somewhere/RebeccaSmith/>
vCard:N
_:b1 .
_:b1
vCard:Family
"Smith" .
_:b1
vCard:Given
"Rebecca" .
<http://somewhere/JohnSmith/>
vCard:FN
"John Smith" .
<http://somewhere/JohnSmith/>
vCard:N
_:b2 .
_:b2
vCard:Family
"Smith" .
_:b2
vCard:Given
"John" .
<http://somewhere/SarahJones/>
vCard:FN
"Sarah Jones" .
<http://somewhere/SarahJones/>
vCard:N
_:b3 .
_:b3
vCard:Family
"Jones" .
_:b3
vCard:Given
Q2
"Sarah" .
15

16. SELECT ?x ?fname
WHERE {
?x <http://www.w3.org/2001/vcard-rdf/3.0#FN> ?fname
}
Q2
---------------------------------------------------| x
| fname
|
====================================================
| <http://somewhere/RebeccaSmith/> | "Becky Smith" |
| <http://somewhere/SarahJones/>
| "Sarah Jones" |
| <http://somewhere/JohnSmith/>
| "John Smith" |
| <http://somewhere/MattJones/>
| "Matt Jones" |
----------------------------------------------------
16

17. PREFIX vCard : <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?givenName
WHERE {
?y
vCard:Family
"Smith" .
?y
vCard:Given
?givenName .
}
<http://somewhere/MattJones/>
vCard:FN
"Matt Jones" .
<http://somewhere/MattJones/>
vCard:N
_:b0 .
_:b0
vCard:Family
"Jones" .
_:b0
vCard:Given
"Matthew" .
<http://somewhere/RebeccaSmith/>
vCard:FN
"Becky Smith" .
<http://somewhere/RebeccaSmith/>
vCard:N
_:b1 .
_:b1
vCard:Family
"Smith" .
_:b1
vCard:Given
"Rebecca" .
<http://somewhere/JohnSmith/>
vCard:FN
"John Smith" .
<http://somewhere/JohnSmith/>
vCard:N
_:b2 .
_:b2
vCard:Family
"Smith" .
_:b2
vCard:Given
"John" .
<http://somewhere/SarahJones/>
vCard:FN
"Sarah Jones" .
<http://somewhere/SarahJones/>
vCard:N
_:b3 .
_:b3
vCard:Family
"Jones" .
_:b3
vCard:Given
Q3
"Sarah" .
17

18. PREFIX vCard : <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?givenName
WHERE {
?y
vCard:Family
"Smith" .
?y
vCard:Given
?givenName .
}
Q3
------------| givenName |
=============
| "John"
|
| "Rebecca" |
-------------
18

19. PREFIX vCard : <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?y
?givenName
WHERE {
?y
vCard:Family
"Smith" .
?y
vCard:Given
?givenName .
}
<http://somewhere/MattJones/>
vCard:FN
"Matt Jones" .
<http://somewhere/MattJones/>
vCard:N
_:b0 .
_:b0
vCard:Family
"Jones" .
_:b0
vCard:Given
"Matthew" .
<http://somewhere/RebeccaSmith/>
vCard:FN
"Becky Smith" .
<http://somewhere/RebeccaSmith/>
vCard:N
_:b1 .
_:b1
vCard:Family
"Smith" .
_:b1
vCard:Given
"Rebecca" .
<http://somewhere/JohnSmith/>
vCard:FN
"John Smith" .
<http://somewhere/JohnSmith/>
vCard:N
_:b2 .
_:b2
vCard:Family
"Smith" .
_:b2
vCard:Given
"John" .
<http://somewhere/SarahJones/>
vCard:FN
"Sarah Jones" .
<http://somewhere/SarahJones/>
vCard:N
_:b3 .
_:b3
vCard:Family
"Jones" .
_:b3
vCard:Given
Q4
"Sarah" .
19

20. PREFIX vCard : <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?y
?givenName
WHERE {
?y
vCard:Family
"Smith" .
?y
vCard:Given
?givenName .
}
Q4
-------------------| y
| givenName |
====================
| _:b1 | "John"
|
| _:b2 | "Rebecca" |
--------------------
20

21. FILTER clause




SPARQL allows to pose restrictions on the values in query
solutions.
These restrictions are defined in FILTER clauses.
These clauses are, to some extent, similar to WHERE clause
of an SQL query.
SPARQL filters can be used to restrict:



string values (using REGEX function),
numeric values (using <, >, =, <=, >= and
!=
operators).
SPARQL also provides test functions:

BOUND, isURI, isBLANK, isLITERAL
21

22. PREFIX vCard : <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?g
WHERE {
?y
vCard:Given
?g .
FILTER regex(?g, "r", "i")
}
<http://somewhere/MattJones/>
vCard:FN
"Matt Jones" .
<http://somewhere/MattJones/>
vCard:N
_:b0 .
_:b0
vCard:Family
"Jones" .
_:b0
vCard:Given
"Matthew" .
<http://somewhere/RebeccaSmith/>
vCard:FN
"Becky Smith" .
<http://somewhere/RebeccaSmith/>
vCard:N
_:b1 .
_:b1
vCard:Family
"Smith" .
_:b1
vCard:Given
"Rebecca" .
<http://somewhere/JohnSmith/>
vCard:FN
"John Smith" .
<http://somewhere/JohnSmith/>
vCard:N
_:b2 .
_:b2
vCard:Family
"Smith" .
_:b2
vCard:Given
"John" .
<http://somewhere/SarahJones/>
vCard:FN
"Sarah Jones" .
<http://somewhere/SarahJones/>
vCard:N
_:b3 .
_:b3
vCard:Family
"Jones" .
_:b3
vCard:Given
Q5
"Sarah" .
22

23. PREFIX vCard : <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?g
WHERE {
?y
vCard:Given
?g .
FILTER regex(?g, "r", "i")
}
Q5
------------| g
|
=============
| "Rebecca" |
| "Sarah"
|
-------------
23

24. Subject
Predicate
Object
<http://somewhere/MattJones/>
vCard:FN
"Matt Jones" .
<http://somewhere/MattJones/>
vCard:N
_:b0 .
_:b0
vCard:Family
"Jones" .
_:b0
vCard:Given
"Matthew" .
<http://somewhere/RebeccaSmith/>
vCard:FN
"Becky Smith" .
<http://somewhere/RebeccaSmith/>
info:age
"2 "^^xsd:integer .
<http://somewhere/RebeccaSmith/>
vCard:N
_:b1 .
_:b1
vCard:Family
"Smith" .
_:b1
vCard:Given
"Rebecca" .
<http://somewhere/JohnSmith/>
vCard:FN
"John Smith" .
<http://somewhere/JohnSmith/>
info:age
"25"^^xsd:integer .
<http://somewhere/JohnSmith/>
vCard:N
_:b2 .
_:b2
vCard:Family
"Smith" .
_:b2
vCard:Given
"John" .
<http://somewhere/SarahJones/>
vCard:FN
"Sarah Jones" .
<http://somewhere/SarahJones/>
vCard:N
_:b3 .
_:b3
vCard:Family
"Jones" .
_:b3
vCard:Given
"Sarah" .
24

25. PREFIX info : <http://somewhere/peopleInfo#>
SELECT ?resource
WHERE {
?resource
info:age
?age .
FILTER (?age <= 24)
}
Q6
<http://somewhere/MattJones/>
vCard:FN
"Matt Jones" .
<http://somewhere/MattJones/>
vCard:N
_:b0 .
_:b0
vCard:Family
"Jones" .
_:b0
vCard:Given
"Matthew" .
<http://somewhere/RebeccaSmith/>
vCard:FN
"Becky Smith" .
<http://somewhere/RebeccaSmith/>
info:age
"2 "^^xsd:integer .
<http://somewhere/RebeccaSmith/>
vCard:N
_:b1 .
_:b1
vCard:Family
"Smith" .
_:b1
vCard:Given
"Rebecca" .
<http://somewhere/JohnSmith/>
vCard:FN
"John Smith" .
<http://somewhere/JohnSmith/>
info:age
"25"^^xsd:integer .
<http://somewhere/JohnSmith/>
vCard:N
_:b2 .
_:b2
vCard:Family
"Smith" .
_:b2
vCard:Given
"John" .
<http://somewhere/SarahJones/>
vCard:FN
"Sarah Jones" .
<http://somewhere/SarahJones/>
vCard:N
_:b3 .
_:b3
vCard:Family
"Jones" .
_:b3
vCard:Given
"Sarah" .
25

26. PREFIX info : <http://somewhere/peopleInfo#>
SELECT ?resource
WHERE {
?resource
info:age
?age .
FILTER (?age <= 24)
}
Q6
-----------------------------------| resource
|
====================================
| <http://somewhere/RebeccaSmith/> |
------------------------------------
26

27. OPTIONAL Clause



SPARQL also allows to define OPTIONAL blocks
They offer the ability to query for data but not to fail query
when that data does not exist.
Optional blocks define additional graph patterns that do bind
to the graph when they can be matched, but do not cause
solutions to be rejected if they are not matched.
27

28. PREFIX info: <http://somewhere/peopleInfo#>
PREFIX vcard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name ?age
WHERE {
?person
vcard:FN
?name .
OPTIONAL { ?person info:age ?age }
}
<http://somewhere/MattJones/>
vCard:FN
"Matt Jones" .
<http://somewhere/MattJones/>
vCard:N
_:b0 .
_:b0
vCard:Family
"Jones" .
_:b0
vCard:Given
"Matthew" .
<http://somewhere/RebeccaSmith/>
vCard:FN
"Becky Smith" .
<http://somewhere/RebeccaSmith/>
info:age
"2 "^^xsd:integer .
<http://somewhere/RebeccaSmith/>
vCard:N
_:b1 .
_:b1
vCard:Family
"Smith" .
_:b1
vCard:Given
"Rebecca" .
<http://somewhere/JohnSmith/>
vCard:FN
"John Smith" .
<http://somewhere/JohnSmith/>
info:age
"25"^^xsd:integer .
<http://somewhere/JohnSmith/>
vCard:N
_:b2 .
_:b2
vCard:Family
"Smith" .
_:b2
vCard:Given
"John" .
<http://somewhere/SarahJones/>
vCard:FN
"Sarah Jones" .
<http://somewhere/SarahJones/>
vCard:N
_:b3 .
_:b3
vCard:Family
"Jones" .
_:b3
vCard:Given
Q7
"Sarah" .
28

29. PREFIX info: <http://somewhere/peopleInfo#>
PREFIX vcard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name ?age
WHERE {
?person
vcard:FN
?name .
OPTIONAL { ?person info:age ?age }
}
Q7
----------------------| name
| age |
=======================
| "Becky Smith" | 23 |
| "Sarah Jones" |
|
| "John Smith" | 25 |
| "Matt Jones" |
|
-----------------------
29

30. PREFIX info: <http://somewhere/peopleInfo#>
PREFIX vcard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name ?age
WHERE {
?person
vcard:FN
?name .
?person
info:age
?age .
}
<http://somewhere/MattJones/>
vCard:FN
"Matt Jones" .
<http://somewhere/MattJones/>
vCard:N
_:b0 .
_:b0
vCard:Family
"Jones" .
_:b0
vCard:Given
"Matthew" .
<http://somewhere/RebeccaSmith/>
vCard:FN
"Becky Smith" .
<http://somewhere/RebeccaSmith/>
info:age
"2 "^^xsd:integer .
<http://somewhere/RebeccaSmith/>
vCard:N
_:b1 .
_:b1
vCard:Family
"Smith" .
_:b1
vCard:Given
"Rebecca" .
<http://somewhere/JohnSmith/>
vCard:FN
"John Smith" .
<http://somewhere/JohnSmith/>
info:age
"25"^^xsd:integer .
<http://somewhere/JohnSmith/>
vCard:N
_:b2 .
_:b2
vCard:Family
"Smith" .
_:b2
vCard:Given
"John" .
<http://somewhere/SarahJones/>
vCard:FN
"Sarah Jones" .
<http://somewhere/SarahJones/>
vCard:N
_:b3 .
_:b3
vCard:Family
"Jones" .
_:b3
vCard:Given
Q8
"Sarah" .
30

31. PREFIX info: <http://somewhere/peopleInfo#>
PREFIX vcard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name ?age
WHERE {
?person
vcard:FN
?name .
?person
info:age
?age .
}
Q8
----------------------| name
| age |
=======================
| "Becky Smith" | 23 |
| "John Smith" | 25 |
-----------------------
31

32. PREFIX info: <http://somewhere/peopleInfo#>
PREFIX vcard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name ?age
WHERE {
?person vcard:FN ?name .
OPTIONAL {
?person info:age ?age .
FILTER ( ?age > 24 )
}
}
<http://somewhere/MattJones/>
vCard:FN
"Matt Jones" .
<http://somewhere/MattJones/>
vCard:N
_:b0 .
_:b0
vCard:Family
"Jones" .
_:b0
vCard:Given
"Matthew" .
<http://somewhere/RebeccaSmith/>
vCard:FN
"Becky Smith" .
<http://somewhere/RebeccaSmith/>
info:age
"2 "^^xsd:integer .
<http://somewhere/RebeccaSmith/>
vCard:N
_:b1 .
_:b1
vCard:Family
"Smith" .
_:b1
vCard:Given
"Rebecca" .
<http://somewhere/JohnSmith/>
vCard:FN
"John Smith" .
<http://somewhere/JohnSmith/>
info:age
"25"^^xsd:integer .
<http://somewhere/JohnSmith/>
vCard:N
_:b2 .
_:b2
vCard:Family
"Smith" .
_:b2
vCard:Given
"John" .
<http://somewhere/SarahJones/>
vCard:FN
"Sarah Jones" .
<http://somewhere/SarahJones/>
vCard:N
_:b3 .
_:b3
vCard:Family
"Jones" .
_:b3
vCard:Given
Q9
"Sarah" .
32

33. PREFIX info: <http://somewhere/peopleInfo#>
PREFIX vcard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name ?age
WHERE {
?person vcard:FN ?name .
OPTIONAL {
?person info:age ?age .
FILTER ( ?age > 24 )
}
}
Q9
----------------------| name
| age |
=======================
| "Becky Smith" |
|
| "Sarah Jones" |
|
| "John Smith" | 25 |
| "Matt Jones" |
|
-----------------------
33

34. PREFIX info: <http://somewhere/peopleInfo#>
PREFIX vcard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name ?age
WHERE {
?person vcard:FN ?name .
OPTIONAL { ?person info:age ?age . }
FILTER ( !bound(?age) || ?age > 24 )
}
<http://somewhere/MattJones/>
vCard:FN
"Matt Jones" .
<http://somewhere/MattJones/>
vCard:N
_:b0 .
_:b0
vCard:Family
"Jones" .
_:b0
vCard:Given
"Matthew" .
<http://somewhere/RebeccaSmith/>
vCard:FN
"Becky Smith" .
<http://somewhere/RebeccaSmith/>
info:age
"2 "^^xsd:integer .
<http://somewhere/RebeccaSmith/>
vCard:N
_:b1 .
_:b1
vCard:Family
"Smith" .
_:b1
vCard:Given
"Rebecca" .
<http://somewhere/JohnSmith/>
vCard:FN
"John Smith" .
<http://somewhere/JohnSmith/>
info:age
"25"^^xsd:integer .
<http://somewhere/JohnSmith/>
vCard:N
_:b2 .
_:b2
vCard:Family
"Smith" .
_:b2
vCard:Given
"John" .
<http://somewhere/SarahJones/>
vCard:FN
"Sarah Jones" .
<http://somewhere/SarahJones/>
vCard:N
_:b3 .
_:b3
vCard:Family
"Jones" .
_:b3
vCard:Given
Q10
"Sarah" .
34

35. PREFIX info: <http://somewhere/peopleInfo#>
PREFIX vcard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name ?age
WHERE {
?person vcard:FN ?name .
OPTIONAL { ?person info:age ?age . }
FILTER ( !bound(?age) || ?age > 24 )
}
Q10
----------------------| name
| age |
=======================
| "Sarah Jones" |
|
| "John Smith" | 25 |
| "Matt Jones" |
|
-----------------------
35

36. @prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix vcard: <http://www.w3.org/2001/vcard-rdf/3.0#> .
_:a
foaf:name
"Matt Jones" .
_:b
foaf:name
"Sarah Jones" .
_:c
vcard:FN
"Becky Smith" .
_:d
vcard:FN
"John Smith" .
36

37. PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX vCard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name
WHERE {
{ []
foaf:name ?name }
UNION
{ []
vCard:FN
?name }
}
_:a
foaf:name
"Matt Jones" .
_:b
foaf:name
"Sarah Jones" .
_:c
vcard:FN
"Becky Smith" .
_:d
vcard:FN
Q11
"John Smith" .
37

38. PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX vCard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name
WHERE {
{ []
foaf:name ?name }
UNION
{ []
vCard:FN
?name }
}
Q11
----------------| name
|
=================
| "Matt Jones" |
| "Sarah Jones" |
| "Becky Smith" |
| "John Smith" |
-----------------
38

39. PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX vCard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name
WHERE {
[]
?p
?name
FILTER ( ?p = foaf:name || ?p = vCard:FN )
}
Q11
----------------| name
|
=================
| "Matt Jones" |
| "Sarah Jones" |
| "Becky Smith" |
| "John Smith" |
-----------------
39

40. PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX vCard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name1 ?name2
WHERE {
{ []
foaf:name ?name1 }
UNION
{ []
vCard:FN
?name2 }
}
_:a
foaf:name
"Matt Jones" .
_:b
foaf:name
"Sarah Jones" .
_:c
vcard:FN
"Becky Smith" .
_:d
vcard:FN
Q12
"John Smith" .
40

41. PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX vCard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name1 ?name2
WHERE {
{ []
foaf:name ?name1 }
UNION
{ []
vCard:FN
?name2 }
}
Q12
--------------------------------| name1
| name2
|
=================================
| "Matt Jones" |
|
| "Sarah Jones" |
|
|
| "Becky Smith" |
|
| "John Smith" |
---------------------------------
41

42. PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX vCard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?name1 ?name2
WHERE {
?x
a
foaf:Person
OPTIONAL { ?x
foaf:name ?name1 }
OPTIONAL { ?x
vCard:FN
?name2 }
}
Q12
--------------------------------| name1
| name2
|
=================================
| "Matt Jones" |
|
| "Sarah Jones" |
|
|
| "Becky Smith" |
|
| "John Smith" |
---------------------------------
42

43. SPARQL Query
PREFIX dc: <http://purl.org/dc/elements/1.1/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX shop: <http://example/shop#>
SELECT ?title ?name ?price
WHERE {
?doc
dc:title
?title .
FILTER regex(?title, "SPARQL") .
?doc
dc:creator
?c .
?c
foaf:name
?name .
OPTIONAL
{ ?doc shop:price ?price }
}
"Find books with ‘SPARQL’ in the title. Get the authors'
name and the price (if available)."
43

44. SPARQL Query Results XML Format

45. SPARQL Query Results XML Format



SPARQL allows query results to be returned as XML
The SPARQL Results Document begins with sparql root element
The sparql element contains two sub-elements, head and results
<?xml version="1.0"?>
<sparql xmlns="http://www.w3.org/2005/sparql-results#">
<head>
...
</head>
<results>
...
</results>
</sparql>
45

46. SPARQL Query Results XML Format



The element head contains a sequence of elements describing the set of
Query Variable names in the query results.
The order of the variable names in the sequence is the order of the variable
names given in the SELECT statement in the SPARQL query
The ordered sequence of variable names are used to create empty child
elements variable with the variable name as the value of an attribute name
<head>
<variable name="name" />
<variable name="homepage" />
<variable name="age" />
</head>
46

47. SPARQL Query Results XML Format



The second child-element of sparql is results

it must appear after head.
The results element contains the complete sequence of query results.
For each Query Solution in the query results, a result child-element of
results is added
<results>
<result>
...
</result>
<result>
...
</result>
...
</results>
47

48. SPARQL Query Results XML Format

Each result element




corresponds to one Query Solution in a result
contains child elements (in no particular order) for each Query Variable that
appears in the solution.
It is used to record how the query variables bind to RDF Terms.
Each binding inside a solution is written as an element binding as a child of
result with the query variable name as the value of the name attribute.
<result>
<binding name="name"> ... </binding>
<binding name="hpage"> ... </binding>
<binding name="age"> ... </binding>
</result>
48

49. SPARQL Query Results XML Format


The value of a query variable binding, which is an RDF Term, is
included as the content of the binding as follows:
RDF URI Reference U
<binding> <uri> U </uri> </binding>

RDF Literal S
<binding> <literal> S </literal> </binding>

RDF Typed Literal S with datatype URI D
<binding> <literal datatype="D"> S </literal>
</binding>
49

50. <?xml version="1.0"?>
<sparql xmlns="http://www.w3.org/2005/sparql-results#">
<head>
<variable name="name"/>
<variable name="hpage"/>
<variable name="age"/>
</head>
<results>
<result>
<binding name="name">
<literal>Bob</literal>
</binding>
<binding name="hpage">
<uri>http://work.example.org/bob/</uri>
</binding>
<binding name="age">
<literal datatype="http://www.w3.org/2001/XMLSchema#integer">
30
</literal>
</binding>
</result>
...
</results>
</sparql>
50

51. References

SPARQL at W3C


http://www.w3.org/TR/rdf-sparql-query/
SPARQL Tutorial

http://jena.sourceforge.net/ARQ/Tutorial/
51