How to handle case-sensitive SPARQL for Wikidata Query Service - sparql

Im trying to perform searchs on wikidata, but my query its a little weird. Some searchs are case-sensitive
EG: using "maradona" match perfectly but "cristiano ronaldo" don't. "Cristiano Ronaldo" match OK.
wikidata
SELECT DISTINCT ?item ?itemLabel (SAMPLE(?RIP) AS ?RIP) (SAMPLE(?image) AS ?image) WHERE {
?item wdt:P31 wd:Q5;
?label "cristiano ronaldo"#en.
?article schema:about ?item;
schema:inLanguage "en".
OPTIONAL { ?item wdt:P570 ?RIP. }
OPTIONAL { ?item wdt:P18 ?image. }
SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}
GROUP BY ?item ?itemLabel
I expect to be able to search all with lowercase (or other way to handle it better)

Related

How to return null results in SPARQL?

I'm using the Wikidata SPARQL Query Service with the following query:
SELECT ?item ?itemLabel ?class ?classLabel ?projectLabel WHERE {
VALUES ?item { wd:Q1 wd:Q367204 }
?item wdt:P31 ?class;
wdt:P18 ?project.
SERVICE wikibase:label { bd:serviceParam wikibase:language "en,en". } }
link to the query
When running the query there is a result for Q1 because there is an image, but there is no result for Q367204 because there isn't an image.
My question: How can I get results for both Q1 and Q367204 regardless if there is an image available or not?
wd:Q367204 is missing from the results because "there isn't an image", but also because there isn't an "instance of" statement (P31). Therefore, you can get results for both instances by wrapping both of these in an OPTIONAL block, with just ?item and ?itemLabel for Q367204, and all variables for Q1:
SELECT ?item ?itemLabel ?class ?classLabel ?projectLabel WHERE {
VALUES ?item { wd:Q1 wd:Q367204 }
OPTIONAL {
?item wdt:P31 ?class;
wdt:P18 ?project.
}
SERVICE wikibase:label { bd:serviceParam wikibase:language "en,en". }
}

Query for EU universities from Wikidata times out

Asking the Wikidata service for all universities works. But when restricted to only EU universities, this query times out.
WHERE {
?item wdt:P31/wdt:P279* wd:Q3918 ;
wdt:P17 ?country.
?country wdt:P463 wd:Q458 .
SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
}
Any idea?
Strangely, using FILTER EXISTS is returns the result (although quite slow).
SELECT ?item ?itemLabel ?countryLabel ?country
WHERE {
?item wdt:P31/wdt:P279* wd:Q3918 ;
wdt:P17 ?country.
FILTER EXISTS { ?country wdt:P463 wd:Q458 }
SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
}
Here's a link to the second query.

Wikidata entries that can't be retrieved by SPARQL queries?

I am trying to run a simple query, looking up an item by its English label. For some reason, some entries are not showing. Most are fine, but some aren't. I can't pinpoint why.
An example: oyster bed. Here is the entry: https://www.wikidata.org/wiki/Q65953972
This is the query:
SELECT distinct ?item ?itemLabel ?itemDescription WHERE {
?item ?label 'oyster bed'#en.
?article schema:about ?item .
?article schema:inLanguage 'en' .
SERVICE wikibase:label { bd:serviceParam wikibase:language 'en'. }
}
and I get nothing.
The same query with oyster yields an expected result.
What am I doing wrong?
Hat tip of #UninformedUser helped.
As a SPARQL newbie, I did not realise the ?article was an implicit JOIN.
SELECT distinct ?item ?itemLabel ?itemDescription WHERE {
?item ?label 'oyster bed'#en.
OPTIONAL { ?article schema:about ?item .
?article schema:inLanguage 'en' . }
SERVICE wikibase:label { bd:serviceParam wikibase:language 'en'. }
}
is to be used if the article is required, but if there is no real need, the query can be simplified to:
SELECT distinct ?item ?itemLabel ?itemDescription WHERE {
?item ?label 'oyster bed'#en.
SERVICE wikibase:label { bd:serviceParam wikibase:language 'en'. }
}

Find people whose name start with a particular letter with sparql Wikidata?

This is my query but I don't get any results for records starting with "n"
SELECT ?item ?itemLabel
WHERE
{
?item wdt:P31/wdt:P279* wd:Q5.
SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
FILTER regex (?itemLabel, "^(n)").
}

Get properties by QID?

I can get item and its properties by label:
SELECT distinct ?item ?itemLabel ?itemDescription
(SAMPLE(?DR) as ?DR) (SAMPLE(?article)as ?article)
WHERE {
?item wdt:P31 wd:Q5.
?item ?label "Einstein"#en
OPTIONAL{?item wdt:P569 ?DR .}
?article schema:about ?item .
?article schema:inLanguage "en" .
?article schema:isPartOf <https://en.wikipedia.org/>.
OPTIONAL{?item wdt:P570 ?RIP .}
OPTIONAL{?item wdt:P18 ?image .}
SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}
GROUP BY ?item ?itemLabel ?itemDescription
See on Wikidata Query Services.
How can I do the same using QID instead label?
Using the URI instead of the variable ?item will get the information based on the entity Albert Einstein:
PREFIX schema: <http://schema.org/>
PREFIX bd: <http://www.bigdata.com/rdf#>
PREFIX wdt: <http://www.wikidata.org/prop/direct/>
PREFIX wikibase: <http://wikiba.se/ontology#>
SELECT DISTINCT ?item ?itemLabel ?itemDescription (SAMPLE(?DR) AS ?DRSample) (SAMPLE(?article) AS ?articleSample)
WHERE
{ ?article schema:about ?item ;
schema:inLanguage "en" ;
schema:isPartOf <https://en.wikipedia.org/>
FILTER ( ?item = <http://www.wikidata.org/entity/Q937> )
OPTIONAL
{ ?item wdt:P569 ?DR }
OPTIONAL
{ ?item wdt:P570 ?RIP }
OPTIONAL
{ ?item wdt:P18 ?image }
SERVICE wikibase:label
{ bd:serviceParam
wikibase:language "en"
}
}
GROUP BY ?item ?itemLabel ?itemDescription
You can utilize the already known QID by using BIND:
BIND(wd:Q937 AS ?item).
...
If you already have the QID of the entity you are looking for and simply look for its properties and labels, you're better off using the Wikidata API wbgetentities module
In A. Einstein (Q937) case, that would give the following API call:
https://www.wikidata.org/w/api.php?action=wbgetentities&ids=Q937&format=json