[Virtuoso-users] Clear graph query problem

[Sebastian Trüg]

Hi list,

With this query:

  clear graph ?mg where {
    ?mg nrl:coreGraphMetadataFor ?g .
    FILTER(?g in (<urn:nepomuk:local:8a9e692a>)) .
    FILTER(
      !bif:exists((select (1) where { graph ?g { ?s ?p ?o . } . }))
    ) .
  }

I get the following error:

  "SP031: SPARQL compiler: non-global variable 'mg' can not be used
   outside any group pattern or result-set list"

Any idea how to fix this? How to remove graphs which are related to
empty graphs the way I am trying in the query?

Cheers,
Sebastian