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countsparql

SPARQL query and distinct count

I have the following query:

SELECT ?tag WHERE {
  ?r ns9:taggedWithTag ?tagresource.
  ?tagresource ns9:name ?tag
}
LIMIT 5000

and the results are:

abc
abc
abc
abc
abc
abc
abc
abd
ads
anb

I want to get somthing like:

tag | count
-----------------
abc     7
abd     1
ads     1
anb     1

I have tried it with count(*) and count(?tag), but than I get the error message "Variable or "*" expected." Can someone tell me, how to make it right?

Solution

  • If you're using Java and Jena's ARQ, you can use ARQ's extensions for aggregates. Your query would look something like:

    SELECT ?tag (count(distinct ?tag) as ?count)
WHERE {
    ?r ns9:taggedWithTag ?tagresource.
    ?tagresource ns9:name ?tag
}
LIMIT 5000

    The original SPARQL specification from 2008 didn't include aggregates, but the current version, 1.1, from 2013 does.