10

Ok so i have this query

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> 

SELECT DISTINCT (COUNT(?instance) AS ?count) WHERE {
?instance a <http://dbpedia.org/ontology/Ambassador> . 
}

and the result is 286. Cool. Now I want to get the number of ambassadors that have http://dbpedia.org/property/name property. But

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> 

SELECT DISTINCT (COUNT(?instance) AS ?count) WHERE {
?instance a <http://dbpedia.org/ontology/Ambassador> . 
?instance <http://dbpedia.org/property/name> ?name
}

results in 533 :(. So it is counting more because there are people which have this property one or more times. But how do I get the number of ambassadors that have this property regardless of how many times they have it. Can you do this in a single query?

Thanks.

ip.
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    As Jonathan's solution shows, your problem isn't duplication, but the fact that you said to get distinct counts, rather than to count distinct instances. The multiple-name issue would only come up if you included both ?instance and ?name in your SELECT... – glenn mcdonald May 12 '11 at 01:38

1 Answers1

14

You might want to try this:

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> 

SELECT (COUNT(DISTINCT ?instance) AS ?count) WHERE {
?instance a <http://dbpedia.org/ontology/Ambassador>; 
          <http://dbpedia.org/property/name> ?name
}

It's giving me a result of 283, which might or might not be right :).

Jonathan
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