Entity Linking - SPARQLqueries

External Identifiers in Wikidata

Wikidata stores thousands of external identifier properties that link entities to other databases. These enable cross-dataset queries and data enrichment.

Property	Database	Domain
`wdt:P214`	VIAF ID	Authority control
`wdt:P227`	GND ID	German National Library
`wdt:P496`	ORCID	Researchers
`wdt:P2037`	GitHub username	Developers
`wdt:P2013`	Facebook ID	Social media
`wdt:P646`	Freebase ID	Knowledge graph

Finding External IDs

All External IDs for a Programming Language

Run ↗

SELECT ?prop ?propLabel ?value
WHERE {
  # Python programming language
  wd:Q28865 ?prop ?value .

  # Filter to external-id properties only
  ?property wikibase:directClaim ?prop ;
             wikibase:propertyType wikibase:ExternalId .

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}

Pattern wikibase:ExternalId — Filter to identifier properties

Museums with VIAF Authority Records

Run ↗

SELECT ?museum ?museumLabel ?viaf
WHERE {
  ?museum wdt:P31/wdt:P279* wd:Q33506 ;  # museum
          wdt:P214 ?viaf .  # has VIAF ID

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}
LIMIT 50

Pattern Domain: Cultural Heritage

Building External URLs

Generate GitHub Profile URLs

Run ↗

SELECT ?person ?personLabel ?github
       (CONCAT("https://github.com/", ?github) AS ?githubUrl)
WHERE {
  ?person wdt:P106 wd:Q5482740 ;  # programmer
          wdt:P2037 ?github .    # GitHub username

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}
LIMIT 30

Pattern CONCAT to build URLs from IDs

Using Formatter URLs

Run ↗

SELECT ?city ?cityLabel ?geonames ?url
WHERE {
  ?city wdt:P31 wd:Q515 ;  # city
        wdt:P17 wd:Q142 ;     # France
        wdt:P1566 ?geonames . # GeoNames ID

  # Get the formatter URL pattern
  wd:P1566 wdt:P1630 ?formatter .
  BIND(IRI(REPLACE(?formatter, "\\$1", ?geonames)) AS ?url)

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}
LIMIT 20

Pattern P1630 — Formatter URL property

Cross-Reference Matching

Find Entity by External ID

Run ↗

SELECT ?item ?itemLabel
WHERE {
  # Find by ORCID
  ?item wdt:P496 "0000-0001-5109-3700" .

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}

Pattern Reverse lookup by external ID

Entities with Multiple Authority IDs

Run ↗

SELECT ?person ?personLabel ?viaf ?gnd ?orcid
WHERE {
  ?person wdt:P106 wd:Q1650915 ;  # researcher
          wdt:P214 ?viaf ;         # VIAF
          wdt:P227 ?gnd ;          # GND
          wdt:P496 ?orcid .        # ORCID

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}
LIMIT 30

Pattern Multi-source linking

Coverage Analysis

Programming Languages Missing GitHub Topic

Run ↗

SELECT ?lang ?langLabel
WHERE {
  ?lang wdt:P31 wd:Q9143 .  # programming language

  # Has no GitHub topic ID
  FILTER NOT EXISTS { ?lang wdt:P9100 ?github . }

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}
LIMIT 50

Pattern Finding missing links

Count External IDs per Entity Type

Run ↗

SELECT ?lang ?langLabel
       (COUNT(DISTINCT ?extProp) AS ?extIdCount)
WHERE {
  ?lang wdt:P31 wd:Q9143 ;  # programming language
        ?extProp ?extValue .

  ?prop wikibase:directClaim ?extProp ;
        wikibase:propertyType wikibase:ExternalId .

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}
GROUP BY ?lang ?langLabel
ORDER BY DESC(?extIdCount)
LIMIT 20

Pattern Measure linking coverage

Key External ID Properties

Property	Name	Domain
`P214`	VIAF ID	People, organizations
`P227`	GND ID	German authority
`P244`	LCNAF	US Library of Congress
`P496`	ORCID	Researchers
`P1566`	GeoNames ID	Geographic places
`P2037`	GitHub username	Developers
`P9100`	GitHub topic	Programming topics
`P856`	Official website	All entities