<s>
SPARQL	B-Language
(	O
pronounced	O
"	O
sparkle	O
"	O
,	O
a	O
recursive	O
acronym	O
for	O
SPARQL	B-Language
Protocol	I-Language
and	I-Language
RDF	I-Language
Query	I-Language
Language	I-Language
)	O
is	O
an	O
RDF	B-Language
query	I-Language
language	I-Language
—	O
that	O
is	O
,	O
a	O
semantic	B-General_Concept
query	I-General_Concept
language	O
for	O
databases	O
—	O
able	O
to	O
retrieve	O
and	O
manipulate	O
data	O
stored	O
in	O
Resource	O
Description	O
Framework	O
(	O
RDF	O
)	O
format	O
.	O
</s>
<s>
It	O
was	O
made	O
a	O
standard	O
by	O
the	O
RDF	O
Data	O
Access	O
Working	O
Group	O
(	O
DAWG	O
)	O
of	O
the	O
World	O
Wide	O
Web	O
Consortium	O
,	O
and	O
is	O
recognized	O
as	O
one	O
of	O
the	O
key	O
technologies	O
of	O
the	O
semantic	B-General_Concept
web	O
.	O
</s>
<s>
On	O
15	O
January	O
2008	O
,	O
SPARQL	B-Language
1.0	O
was	O
acknowledged	O
by	O
W3C	O
as	O
an	O
official	O
recommendation	O
,	O
and	O
SPARQL	B-Language
1.1	O
in	O
March	O
,	O
2013	O
.	O
</s>
<s>
SPARQL	B-Language
allows	O
for	O
a	O
query	O
to	O
consist	O
of	O
triple	O
patterns	O
,	O
conjunctions	O
,	O
disjunctions	O
,	O
and	O
optional	O
patterns	O
.	O
</s>
<s>
There	O
exist	O
tools	O
that	O
allow	O
one	O
to	O
connect	O
and	O
semi-automatically	O
construct	O
a	O
SPARQL	B-Language
query	O
for	O
a	O
SPARQL	B-Language
endpoint	I-Language
,	O
for	O
example	O
ViziQuer	O
.	O
</s>
<s>
In	O
addition	O
,	O
tools	O
exist	O
to	O
translate	O
SPARQL	B-Language
queries	O
to	O
other	O
query	B-Language
languages	I-Language
,	O
for	O
example	O
to	O
SQL	B-Language
and	O
to	O
XQuery	B-Language
.	O
</s>
<s>
SPARQL	B-Language
allows	O
users	O
to	O
write	O
queries	O
against	O
what	O
can	O
loosely	O
be	O
called	O
"	O
key-value	O
"	O
data	O
or	O
,	O
more	O
specifically	O
,	O
data	O
that	O
follow	O
the	O
RDF	O
specification	O
of	O
the	O
W3C	O
.	O
</s>
<s>
This	O
is	O
analogous	O
to	O
some	O
NoSQL	B-General_Concept
databases	O
 '	O
usage	O
of	O
the	O
term	O
"	O
document-key-value	O
"	O
,	O
such	O
as	O
MongoDB	B-Application
.	O
</s>
<s>
In	O
SQL	B-Language
relational	B-Application
database	I-Application
terms	O
,	O
RDF	O
data	O
can	O
also	O
be	O
considered	O
a	O
table	O
with	O
three	O
columns	O
–	O
the	O
subject	O
column	O
,	O
the	O
predicate	O
column	O
,	O
and	O
the	O
object	O
column	O
.	O
</s>
<s>
The	O
subject	O
in	O
RDF	O
is	O
analogous	O
to	O
an	O
entity	O
in	O
a	O
SQL	B-Language
database	I-Language
,	O
where	O
the	O
data	O
elements	O
(	O
or	O
fields	O
)	O
for	O
a	O
given	O
business	O
object	O
are	O
placed	O
in	O
multiple	O
columns	O
,	O
sometimes	O
spread	O
across	O
more	O
than	O
one	O
table	O
,	O
and	O
identified	O
by	O
a	O
unique	B-Application
key	I-Application
.	O
</s>
<s>
In	O
RDF	O
,	O
those	O
fields	O
are	O
instead	O
represented	O
as	O
separate	O
predicate/object	O
rows	O
sharing	O
the	O
same	O
subject	O
,	O
often	O
the	O
same	O
unique	B-Application
key	I-Application
,	O
with	O
the	O
predicate	O
being	O
analogous	O
to	O
the	O
column	O
name	O
and	O
the	O
object	O
the	O
actual	O
data	O
.	O
</s>
<s>
Unlike	O
relational	B-Application
databases	I-Application
,	O
the	O
object	O
column	O
is	O
heterogeneous	O
:	O
the	O
per-cell	O
data	O
type	O
is	O
usually	O
implied	O
(	O
or	O
specified	O
in	O
the	O
ontology	O
)	O
by	O
the	O
predicate	O
value	O
.	O
</s>
<s>
Also	O
unlike	O
SQL	B-Language
,	O
RDF	O
can	O
have	O
multiple	O
entries	O
per	O
predicate	O
;	O
for	O
instance	O
,	O
one	O
could	O
have	O
multiple	O
"	O
child	O
"	O
entries	O
for	O
a	O
single	O
"	O
person	O
"	O
,	O
and	O
can	O
return	O
collections	O
of	O
such	O
objects	O
,	O
like	O
"	O
children	O
"	O
.	O
</s>
<s>
Thus	O
,	O
SPARQL	B-Language
provides	O
a	O
full	O
set	O
of	O
analytic	O
query	O
operations	O
such	O
as	O
JOIN	O
,	O
SORT	O
,	O
AGGREGATE	O
for	O
data	O
whose	O
schema	B-Application
is	O
intrinsically	O
part	O
of	O
the	O
data	O
rather	O
than	O
requiring	O
a	O
separate	O
schema	B-Application
definition	O
.	O
</s>
<s>
However	O
,	O
schema	B-Application
information	O
(	O
the	O
ontology	O
)	O
is	O
often	O
provided	O
externally	O
,	O
to	O
allow	O
joining	O
of	O
different	O
datasets	O
unambiguously	O
.	O
</s>
<s>
In	O
addition	O
,	O
SPARQL	B-Language
provides	O
specific	O
graph	B-Application
traversal	O
syntax	O
for	O
data	O
that	O
can	O
be	O
thought	O
of	O
as	O
a	O
graph	B-Application
.	O
</s>
<s>
This	O
query	O
returns	O
the	O
?	O
name	O
and	O
?	O
email	O
because	O
?	O
person	O
is	O
often	O
a	O
complex	O
URI	B-Protocol
rather	O
than	O
a	O
human-friendly	O
string	O
.	O
</s>
<s>
This	O
query	O
can	O
be	O
distributed	O
to	O
multiple	O
SPARQL	B-Language
endpoints	I-Language
(	O
services	O
that	O
accept	O
SPARQL	B-Language
queries	O
and	O
return	O
results	O
)	O
,	O
computed	O
,	O
and	O
results	O
gathered	O
,	O
a	O
procedure	O
known	O
as	O
federated	B-Operating_System
query	I-Operating_System
.	O
</s>
<s>
In	O
the	O
case	O
of	O
queries	O
that	O
read	O
data	O
from	O
the	O
database	O
,	O
the	O
SPARQL	B-Language
language	O
specifies	O
four	O
different	O
query	O
variations	O
for	O
different	O
purposes	O
.	O
</s>
<s>
SELECT	O
query	O
Used	O
to	O
extract	O
raw	O
values	O
from	O
a	O
SPARQL	B-Language
endpoint	I-Language
,	O
the	O
results	O
are	O
returned	O
in	O
a	O
table	O
format	O
.	O
</s>
<s>
CONSTRUCT	O
query	O
Used	O
to	O
extract	O
information	O
from	O
the	O
SPARQL	B-Language
endpoint	I-Language
and	O
transform	O
the	O
results	O
into	O
valid	O
RDF	O
.	O
</s>
<s>
ASK	O
query	O
Used	O
to	O
provide	O
a	O
simple	O
True/False	O
result	O
for	O
a	O
query	O
on	O
a	O
SPARQL	B-Language
endpoint	I-Language
.	O
</s>
<s>
DESCRIBE	O
query	O
Used	O
to	O
extract	O
an	O
RDF	O
graph	B-Application
from	O
the	O
SPARQL	B-Language
endpoint	I-Language
,	O
the	O
content	O
of	O
which	O
is	O
left	O
to	O
the	O
endpoint	O
to	O
decide	O
,	O
based	O
on	O
what	O
the	O
maintainer	O
deems	O
as	O
useful	O
information	O
.	O
</s>
<s>
SPARQL	B-Language
1.1	O
specifies	O
a	O
language	O
for	O
updating	O
the	O
database	O
with	O
several	O
new	O
query	O
forms	O
.	O
</s>
<s>
Another	O
SPARQL	B-Language
query	O
example	O
that	O
models	O
the	O
question	O
"	O
What	O
are	O
all	O
the	O
country	O
capitals	O
in	O
Africa	O
?	O
</s>
<s>
The	O
SPARQL	B-Language
query	O
processor	O
will	O
search	O
for	O
sets	O
of	O
triples	O
that	O
match	O
these	O
four	O
triple	O
patterns	O
,	O
binding	O
the	O
variables	O
in	O
the	O
query	O
to	O
the	O
corresponding	O
parts	O
of	O
each	O
triple	O
.	O
</s>
<s>
To	O
make	O
queries	O
concise	O
,	O
SPARQL	B-Language
allows	O
the	O
definition	O
of	O
prefixes	O
and	O
base	O
URIs	B-Protocol
in	O
a	O
fashion	O
similar	O
to	O
Turtle	O
.	O
</s>
<s>
GeoSPARQL	B-General_Concept
defines	O
filter	O
functions	O
for	O
geographic	B-Application
information	I-Application
system	I-Application
(	O
GIS	B-Application
)	O
queries	O
using	O
well-understood	O
OGC	O
standards	O
(	O
GML	O
,	O
WKT	B-Language
,	O
etc	O
.	O
</s>
<s>
SPARUL	B-General_Concept
is	O
another	O
extension	O
to	O
SPARQL	B-Language
.	O
</s>
<s>
It	O
enables	O
the	O
RDF	O
store	O
to	O
be	O
updated	O
with	O
this	O
declarative	O
query	B-Language
language	I-Language
,	O
by	O
adding	O
INSERT	O
and	O
DELETE	O
methods	O
.	O
</s>
<s>
XSPARQL	O
is	O
an	O
integrated	O
query	B-Language
language	I-Language
combining	O
XQuery	B-Language
with	O
SPARQL	B-Language
to	O
query	O
both	O
XML	O
and	O
RDF	O
data	O
sources	O
at	O
once	O
.	O
</s>
<s>
See	O
List	B-Language
of	I-Language
SPARQL	I-Language
implementations	I-Language
for	O
more	O
comprehensive	O
coverage	O
,	O
including	O
triplestore	O
,	O
APIs	B-General_Concept
,	O
and	O
other	O
storages	O
that	O
have	O
implemented	O
the	O
SPARQL	B-Language
standard	O
.	O
</s>
