[JENA-1203] projecting non grouped variable in subquery is incorrectly allowed

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: Jena 3.1.1

Environment

sparql.org's validator

• Assignee: Andy Seaborne
• Reporter: Joshua Taylor
• Created: 01/Jul/16 17:15
• Updated: 08/Nov/16 10:21
• Resolved: 13/Jul/16 13:20

Description

Described in this Stack Overflow answer, http://stackoverflow.com/a/38104783/1281433 :

SELECT ?sub ?pred ?obj (count(?obj) as ?count)
    WHERE { ?sub ?pred ?obj .
        } GROUP BY ?sub

is illegal, because there are non-grouped variables in the projection (?pred, ?obj). However, when this query appears as a subquery, no syntax error is reported, as in:

DELETE { ?sub ?pred ?obj . } 
WHERE {  
    {SELECT ?sub ?pred ?obj (count(?obj) as ?count)
    WHERE { ?sub ?pred ?obj .
        } GROUP BY ?sub
    } FILTER(?count < 14)
}