I am trying to get list of all the authors who have had more than 3 piece of work - DBpedia Sparql

Question

I am trying to get list of all the authors who have had 3 or more piece of work done (in DBpedia).

my example can be run on : http://dbpedia.org/sparql

base co

Answer 1

Using HAVING is correct, but there is a limitation in SPARQL with indirectly referring to aggregates.

This one works:

SELECT (count(?work) as ?tw) ?author
WHERE
{
  ?work dbo:author ?author.
}
GROUP BY ?author
HAVING (count(?work) > 3)

Answer 2

HAVING (?tw > 3) is correct SPARQL. HAVING filters after assignments due to SELECT, so ?tw is visible, and before projection.

(prefix ((dbo: <http://purl.org/dc/elements/1.1/>))
    (project (?tw ?author)
      (filter (> ?tw 3)
        (extend ((?tw ?.0))
          (group (?author) ((?.0 (count ?work)))
            (bgp (triple ?work dbo:author ?author)))))))

where ?.0 is the assignment of count.