[jira] [Commented] (JENA-1327) HAVING clause accepts projected expression

["Andy Seaborne (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JENA-1327?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15984397#comment-15984397 ] 

Andy Seaborne commented on JENA-1327:
-------------------------------------

It is correct.

{{HAVING}} is {{FILTER}} applied after aggregation sop {{?tw}} is in-scope. (The keyword nearly was {{FILTER}} not {{HAVING}} which is an SQL-hangover.)

{{SELECT}} does many things - not all of them happen at the point of projection.

Try the query at the [sparql.org query validator|http://www.sparql.org/validate/query].

{noformat}
PREFIX  dbo:  <http://purl.org/dc/elements/1.1/>

SELECT  (COUNT(?work) AS ?tw) ?author
WHERE
  { ?work  dbo:author  ?author }
GROUP BY ?author
HAVING ( ?tw > 3 )

===> Algebra structure

(base <http://example/base/>
  (prefix ((dbo: <http://purl.org/dc/elements/1.1/>))
    (project (?tw ?author)
      (filter (> ?tw 3)                     <----- Due to HAVING
        (extend ((?tw ?.0))
          (group (?author) ((?.0 (count ?work)))
            (bgp (triple ?work dbo:author ?author))))))))
{noformat}
Note the position of {{(project)}} and the {{(count)}}, all from {{SELECT}}.


> HAVING clause accepts projected expression
> ------------------------------------------
>
>                 Key: JENA-1327
>                 URL: https://issues.apache.org/jira/browse/JENA-1327
>             Project: Apache Jena
>          Issue Type: Question
>          Components: ARQ
>    Affects Versions: Jena 3.1.1, Jena 3.2.0
>            Reporter: Lorenz Bühmann
>            Priority: Minor
>
> I'm wondering whether the SPARQL parser is correct with accepting the following query:
> {noformat}
> PREFIX  dbo:  <http://purl.org/dc/elements/1.1/>
> SELECT  (COUNT(?work) AS ?tw) ?author
> WHERE
>   { ?work  dbo:author  ?author }
> GROUP BY ?author
> HAVING ( ?tw > 3 )
> {noformat}
> According to the [specs|https://www.w3.org/TR/sparql11-query/#sparqlHavingClause], I would assume that this is not allowed and one has to use
> {noformat}
> PREFIX  dbo:  <http://purl.org/dc/elements/1.1/>
> SELECT  (COUNT(?work) AS ?tw) ?author
> WHERE
>   { ?work  dbo:author  ?author }
> GROUP BY ?author
> HAVING ( COUNT(?tw) > 3 )
> {noformat}
> But as always, I might misunderstand the specs. 



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