Aggregate

COUNT

Count the number of results. COUNT is the most common aggregate function, used to tally items, relationships, or any matching patterns.

Understanding COUNT

COUNT returns the number of items that match a pattern. Use COUNT(*) to count all rows, or COUNT(?var) to count non-null values.

Syntax	Description
`COUNT(*)`	Count all matching rows
`COUNT(?var)`	Count non-null values
`COUNT(DISTINCT ?var)`	Count unique values

Basic Counting

Count All Countries

Run ↗

SELECT (COUNT(?country) AS ?count)
WHERE {
  ?country wdt:P31 wd:Q6256 .
}

Aggregate Total number of countries in Wikidata

Count with DISTINCT

Run ↗

SELECT (COUNT(DISTINCT ?country) AS ?uniqueCountries)
WHERE {
  ?city wdt:P17 ?country .
  ?city wdt:P31 wd:Q515 .
}

Aggregate Count unique countries that have cities

COUNT with GROUP BY

Cities per Country

Run ↗

SELECT ?country ?countryLabel (COUNT(?city) AS ?cityCount)
WHERE {
  ?city wdt:P31 wd:Q515 ;
        wdt:P17 ?country .
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}
GROUP BY ?country ?countryLabel
ORDER BY DESC(?cityCount)
LIMIT 10

Aggregate Top 10 countries by number of cities

Works per Author

Run ↗

SELECT ?author ?authorLabel (COUNT(?work) AS ?workCount)
WHERE {
  ?work wdt:P50 ?author .
  ?author wdt:P31 wd:Q5 .
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}
GROUP BY ?author ?authorLabel
ORDER BY DESC(?workCount)
LIMIT 10

Aggregate Most prolific authors by work count