SPARQL MINUS Clause: Excluding Unwanted Matches from Query Results

  

When building SPARQL queries, it's common to combine graph patterns to retrieve exactly the data you need. So far we've seen several ways to combine patterns:

 

·      Conjunction (.) — retrieve data that satisfies multiple conditions.

·      OPTIONAL — retrieve additional information when it exists.

·      UNION — combine results from alternative graph patterns.

 

There is one more useful construct: MINUS. The MINUS clause allows us to remove solutions that match a specific graph pattern from our result set. While similar results can often be achieved using FILTER or FILTER NOT EXISTS, MINUS provides a clear and declarative way to express exclusion.

 

Let's explore this using our Marvel RDF dataset.

 

Suppose we want to retrieve the names of all superheroes in our Marvel knowledge graph.

 

Query Without MINUS

PREFIX : <http://example.org/marvel/>

SELECT ?heroName
WHERE {
    ?hero a :Superhero ;
          :name ?heroName .
}
ORDER BY ?heroName

Output

heroName
Black Widow
Captain America
Hulk
Iron Man
Star-Lord
Thor

   

Now imagine we want the same list but we do not want to include Hulk.

SPARQL provides a dedicated construct for exclusion: MINUS.

 

PREFIX : <http://example.org/marvel/>

SELECT ?heroName
WHERE {
    ?hero a :Superhero ;
          :name ?heroName .

    MINUS {
        ?hero a :Superhero ;
          :name "Hulk" .
    }
}
ORDER BY ?heroName

   

Output

 

heroName
Black Widow
Captain America
Iron Man
Star-Lord
Thor

   

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