On 28/01/13 12:56, Rob Walpole wrote:
Hello,
Hoping for some help with troublesome query...
I have a number of resources that are related in a parent/child
hierarchy. I need to perform a query that identifies the other children
of resources belonging to an ancestor path. In other words if I have
resource x then i want to find x's aunt, great-aunt, great-great-aunt
and so on, if they exist (we are not talking about people here - I am
only using the term aunt to explain the relationship).
My resources have a property which identifies their parent resource
(there is only ever one parent) and I am using a SPARQL 1.1 property
path to find the ancestors, e.g.
?resource :parent+ ?ancestor .
I am then finding the immediate children of these ancestors as follows:
?child :parent ?ancestor .
...and I have confirmed that ?ancestor and ?child contain the exact
resources that I would expect. The final solution however requires me to
find all of the child resources that are not ancestors and this I cannot
get to work. I thought the answer would be simply be...
FILTER(?child != ?ancestor)
but this has no affect and ?child still contains duplicates of resources
in ?ancestors.
FILTER tests the values of a variable in the current row, not all
possible values of a variable anywhere. Only loops in the data will
:X :parent :X
will be != excluded.
What you need to do is check the data to see if what ever value ?child
has, then it is not used as an ancestor. The value of ?ancestor in the
row is only one match, not all matches.
Something like:
FILTER NOT EXISTS { [] :parent ?child }
or
FILTER NOT EXISTS { ?someNewVar :parent ?child }
which checks to that ?child is not also used as an object of :parent
(and hence would be in ?ancestor).
For completeness the full query is attached. I am executing this query
against a Jena Fuseki SPARQL endpoint.
Other:
FILTER(?ancestor IN(?member)) .
?member is not a list of values - in any given row, it is one value so
IN is not going to be any different from
FILTER(?ancestor = ?member)
Ditto use of "dri:parent+ ?ancestor , ?ancestorPath ."
I suspect you mean a NOT EXISTS or EXISTS test of some kind.
Thanks
Rob
Andy
