My SPARQL code out of the Learning SPARQL book:
Contruct
{
?s dm:problem dm:prob29 .
dm:prob29 rdfs:label "Location value must be a URI." .
}
WHERE
{
?s dm:location ?city .
FILTER (!(isURI(?city)))
}
-- creates a file like this:
dm:prob29 rdfs:label "Location value must be a URI." .
d:item693 dm:problem dm:prob29 .enter
Why does he create the "Location value must be URI" triple first, when in the Contruct command dm:prob29 etc. is shown first? I am not really sure how this work?
The order of such triples is arbitrary, and has no importance nor meaning, in the context of a CONSTRUCT query's output.
Related
I have the following query
CONSTRUCT{
?entity a something;
a label ?label .
}
WHERE
{
?entity a something;
a label ?label .
BIND(CONCAT(STR( ?label ), " | SOME ADDITIONAL TEXT I WOULD LIKE TO APPEND MANUALLY") ) AS ?label ) .
}
I simply want to concatenate some text with ?label, however when running the query I get the following error:
BIND clause alias '?label' was previously used
I only want to return a single instance of ?label hence, I defined it in the construct clause.
The error message seems to be accurate, but is only the first of many you will get with this query. The usual request to take a look at some SPARQL learning resources to at least understand the basics of triple-based graph pattern matching, along with, a couple of hints one what to look for. CONSTRUCT isn't a bad place to start, and the following should almost do what I think you intend:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
CONSTRUCT{
?entity rdfs:label ?label .
}
WHERE
{
?entity a ex:something ;
rdfs:label ?oldlabel .
BIND(CONCAT(STR( ?oldlabel ), " | SOME ADDITIONAL TEXT I WOULD LIKE TO APPEND MANUALLY") ) AS ?label ) .
}
There's quite a few things different about that query, so take a look to see if it accurately does what you want. One hint is the syntactic difference between using '.' and ';' to separate the triple patterns. Another is that each clause defines either a URL, using a qname in the example, or a variable, prefixed by a '?'. Neither 'label' or 'something' are valid.
I say "almost" because CONSTRUCT only returns a set of triples. To modify the labels, which I think is the intent, you need to use SPARQL Update, i.e.:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX ex: <http://example.org/example#>
DELETE {
?entity rdfs:label ?oldlabel .
}
INSERT{
?entity rdfs:label ?label .
}
WHERE
{
?entity a ex:something .
?entity rdfs:label ?oldlabel .
BIND(CONCAT(STR( ?oldlabel ), " | SOME ADDITIONAL TEXT I WOULD LIKE TO APPEND MANUALLY") AS ?label ) .
}
Note how the triple pattern finds matches for ?oldlabel and deletes them, inserting the newly bound ?label instead. This query assumes a default graph is defined that holds both the original data and the target for updates. If not then the graph needs to be specified using WITH or GRAPH. (Also included another hint on the syntactic difference between using '.' and ';' to separate triple patterns.)
Is it possible to execute SPARQL construct while adding information outside the scope of query? e.g., I want to execute SPARQL construct while defining enumeration information like this:
PREFIX skos:<http://www.w3.org/2004/02/skos/core#>
construct {
?s a skos:Concept
?s ex:index <enumeration starting from 1 -- this is just a sample>
}
where {
?s a skos:Concept
}
is it possible to do something like that with pure SPARQL? what are the alternatives?
* Additional Information *
Probably I am not explained my problem clearly, so basically I want to achieve the following (assuming that ex:index is a valid datatypeProperty):
== Initial RDF triples ==
#prefix skos:<http://www.w3.org/2004/02/skos/core#>
#prefix ex: <http://example.org/> .
ex:abc rdf:type skos:Concept .
ex:def rdf:type skos:Concept .
...
ex:endOfSample rdf:type skos:Concept .
== RDF triples after SPARQL Update execution ==
#prefix skos:<http://www.w3.org/2004/02/skos/core#>
#prefix ex: <http://example.org/> .
ex:abc rdf:type skos:Concept ;
ex:index 1 .
ex:def rdf:type skos:Concept ;
ex:index 2 .
...
ex:endOfSample rdf:type skos:Concept ;
ex:index <endOfSampleNumber> .
You can construct any valid RDF value in a CONSTRUCT. However the query will fail if any of the variables in the CONSTRUCT graph pattern is unbound after executing the WHERE graph. I.e. there can be no binding for ?p in your query and the CONSTRUCT will never execute.
This is an example that should get you started:
PREFIX skos:<http://www.w3.org/2004/02/skos/core#>
PREFIX ex:<http://example.org/construct#>
construct {
ex:someProp a owl:ObjectProperty .
?s ex:someProp (1 2 3)
}
where {
?s a skos:Concept
}
This will result in the construction of seven triples for the property value and the list structure.
The ex:someProp is added because there isn't a good object property in SKOS for ad-hoc lists. It would be best to define the property with some semantic meaning. Also note that while the {ex:someProp a owl:ObjectProperty} triple will be asserted for each match of {?s a skos:Concept}, it is the same triple, hence there will be only one in the end. The price is efficiency, so asserting the property outside of this query would be a better choice - it is included in the above query for the sake of example completeness.
I am trying this query:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?label
WHERE
{
?AGE rdfs:label ?label.
}
I need all the values of AGE from my model but instead this query is giving me other resources values which have the same property label .
For example I have connected the resource gender to have a property rdfs:label. So in my result I get both age values and gender values.
Can anybody tell me where am I wrong ?
It seems you may be assigning some semantics to the variable '?AGE'. SPARQL is a graph pattern matching language and anything with a '?' as the first character is a variable - or better yet, an unknown in the graph pattern match. I.e., the following is an equivalent query to yours:
SPARQL ?label
WHERE
{ ?s rdfs:label ?label .
}
This will find all triples that have a rdfs:label property and select the value of ?label.
If you have a specific resource you want to query, then specify that resource in the subject, for example:
PREFIX ex: <http://example.org/ex>
SPARQL ?label
WHERE
{ ex:AGE rdfs:label ?label .
}
So understanding the difference between an unknown (denoted by '?' (or '$')) and a known (a qname or a full URI) is important to understand how SPARQL performs graph pattern matching.
Lots of SPARQL learning material on the Web, so a suggestion is to look into some of these to learn some basics.
I am new to sparql and I am trying to search a word in one of the property . The simple queries works fine but I don't know how to perform full text search . I saw this example on jena website :
PREFIX text: <http://jena.apache.org/text#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?s
{ ?s text:query (rdfs:label 'word' 10) ;
rdfs:label ?label
}
my model contains property named SUB: and I want to write a query for that . I don't understand what is text and query in text:query means in the above example . Pardon me if this question doesn't meet the requirements of SO.
Link to website:http://jena.apache.org/documentation/query/text-query.html
You may not need a full text index:
SELECT ?s
{ ?s your:property ?o .
FILTER regex(str(?o), "word", "i")
}
but if you do text:query is a "property function" -- it trigger accessing the Apache Lucene index and causing ?s to be bound to each of the answers from a match of 'word' (to a limit of 10) over the rdfs:label properties if you have correctly configured and loaded the data and index.
I need a Sparql query to recover the Type of a specific DBpedia resource. Eg.:
pt.DBpedia resource: http://pt.dbpedia.org/resource/Argentina
Expected type: Country (as can be seen at http://pt.dbpedia.org/page/Argentina)
Using pt.DBpedia Sparql Virtuoso Interface (http://pt.dbpedia.org/sparql) I have the query below:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
select ?l ?t where {
?l rdfs:label "Argentina"#pt .
?l rdf:type ?t .
}
But it is not recovering anything, just print the variable names. The virtuoso answer.
Actually I do not need to recover the label (?l) too.
Anyone can fix it, or help me to define the correct query?
http in graph name
I'm not sure how you generated your query string, but when I copy and paste your query into the endpoint and run it, I get results, and the resulting URL looks like:
http://pt.dbpedia.org/sparql?default-graph-uri=http%3A%2F%2Fpt.dbpedia.org&sho...
However, the link in your question is:
http://pt.dbpedia.org/sparql?default-graph-uri=pt.dbpedia.org%2F&should-sponge...
If you look carefully, you'll see that the default-graph-uri parameters are different:
yours: pt.dbpedia.org%2F
mine: http%3A%2F%2Fpt.dbpedia.org
I'm not sure how you got a URL like the one you did, but it's not right; the default-graph-uri needs to be http://pt.dbpedia.org, not pt.dbpedia.org/.
The query is fine
When I run the query you've provided at the endpoint you've linked to, I get the results that I'd expect. It's worth noting that the label here is the literal "Argentina"#pt, and that what you've called ?l is the individual, not the label. The individual ?l has the label "Argentina"#pt.
We can simplify your query a bit, using ?i instead of ?l (to suggest individual):
select ?i ?type where {
?i rdfs:label "Argentina"#pt ;
a ?type .
}
When I run this at the Portuguese endpoint, I get these results:
If you don't want the individual in the results, you don't have to select it:
select ?type where {
?i rdfs:label "Argentina"#pt ;
a ?type .
}
or even:
select ?type where {
[ rdfs:label "Argentina"#pt ; a ?type ]
}
If you know the identifier of the resource, and don't need to retrieve it by using its label, you can even just do:
select ?type where {
dbpedia-pt:Argentina a ?type
}
type
==========================================
http://www.w3.org/2002/07/owl#Thing
http://www.opengis.net/gml/_Feature
http://dbpedia.org/ontology/Place
http://dbpedia.org/ontology/PopulatedPlace
http://dbpedia.org/ontology/Country
http://schema.org/Place
http://schema.org/Country