FILTER - SPARQLqueries

Understanding FILTER

FILTER tests each potential result against a boolean condition. Only results where the condition evaluates to true are included in the output.

Operator	Meaning	Example
`=`	Equal	`?x = 100`
`!=`	Not equal	`?x != 0`
`<`, `>`	Less/greater than	`?pop > 1000000`
`<=`, `>=`	Less/greater or equal	`?year >= 2000`
`&&`	Logical AND	`?a > 0 && ?a < 100`
`\|\|`	Logical OR	`?type = "A" \|\| ?type = "B"`
`!`	Logical NOT	`!BOUND(?x)`

Numeric Comparisons

Filter by Population

Run ↗

SELECT ?country ?countryLabel ?population
WHERE {
  ?country wdt:P31 wd:Q6256 ;
           wdt:P1082 ?population .
  FILTER(?population > 100000000)
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}
ORDER BY DESC(?population)

Basic Countries with more than 100 million people

This query finds countries (Q6256) with populations exceeding 100 million. The FILTER clause tests each country's population value.

Range Filter

Run ↗

SELECT ?mountain ?mountainLabel ?elevation
WHERE {
  ?mountain wdt:P31 wd:Q8502 ;
            wdt:P2044 ?elevation .
  FILTER(?elevation >= 8000 && ?elevation < 9000)
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}
ORDER BY DESC(?elevation)

Basic Eight-thousanders (peaks 8000m to 9000m)

Use && to combine conditions. This finds mountains between 8000 and 9000 meters — the famous "eight-thousanders."

String Functions in FILTER

Filter by Label Content

Run ↗

SELECT ?city ?cityLabel
WHERE {
  ?city wdt:P31 wd:Q515 ;
        rdfs:label ?cityLabel .
  FILTER(LANG(?cityLabel) = "en")
  FILTER(STRSTARTS(?cityLabel, "New"))
}
LIMIT 20

Basic Cities whose English names start with "New"

String functions like STRSTARTS(), CONTAINS(), and REGEX() let you filter by text patterns. The LANG() function checks the language tag of a literal.

Regular Expression Filter

Run ↗

SELECT ?person ?personLabel
WHERE {
  ?person wdt:P31 wd:Q5 ;
          wdt:P106 wd:Q82955 ;
          rdfs:label ?personLabel .
  FILTER(LANG(?personLabel) = "en")
  FILTER(REGEX(?personLabel, "Einstein$"))
}

Basic Politicians whose names end with "Einstein"

REGEX supports full regular expressions. The $ anchors the match to the end of the string. Use "i" as a third argument for case-insensitive matching.

Existence Tests

Filter by Bound Variable

Run ↗

SELECT ?person ?personLabel ?spouse ?spouseLabel
WHERE {
  ?person wdt:P31 wd:Q5 ;
          wdt:P106 wd:Q901 .
  OPTIONAL { ?person wdt:P26 ?spouse . }
  FILTER(!BOUND(?spouse))
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}
LIMIT 20

Basic Scientists without a recorded spouse

BOUND(?var) tests whether a variable has a value. Combined with OPTIONAL, !BOUND(?var) finds items that lack a particular property.

Key Entities Used in Examples

Entity	Description
`wd:Q5`	Human
`wd:Q515`	City
`wd:Q6256`	Country
`wd:Q8502`	Mountain
`wd:Q82955`	Politician
`wd:Q901`	Scientist
`wdt:P26`	Spouse
`wdt:P31`	Instance of
`wdt:P106`	Occupation
`wdt:P1082`	Population
`wdt:P2044`	Elevation