Column result unexpectedly returning nothing - sparql

Question

Have a SPARQL query that returns nothing for Airport_Name when I believe it should.
PREFIX nas: <https://data.nasa.gov/ontologies/atmonto/NAS#>
PREFIX gen: <https://data.nasa.gov/ontologies/atmonto/general#>
SELECT *
WHERE{
{
{SELECT ?Airport_Name{
?Airport rdf:type nas:Airport ;
nas:airportName ?Airport_Name .
}
}
}UNION{
?Location rdf:type gen:PointLocation;
gen:longitude ?X ;
gen:latitude ?Y .
}
?Location rdf:type gen:PointLocation;
gen:longitude ?X ;
gen:latitude ?Y .
FILTER (?X > -80 && ?X < -64 && ?Y > 18 && ?Y < 32)
}
Expected result should return Location, X, Y, and Airport_Name
When I try to return Airport_Name at the bottom, the Location columns then appear blank, so im not sure what has been done wrongly. If anyone could point me in the right direction, that would be much appreciated.

Answer 1

Your query has several issues, the correct query would be something like below.
Query
SELECT *
WHERE
{ ?airport rdf:type/rdfs:subClassOf* nas:Airport ;
nas:airportName ?Airport_Name ;
nas:airportLocation ?location .
?location gen:longitude ?X ;
gen:latitude ?Y
FILTER ( ?X > "-80"^^xsd:float && ?X < "-64"^^xsd:float && ?Y > "18"^^xsd:float && ?Y < "32"^^xsd:float )
}
Result (sample with LIMIT 10)
--------------------------------------------------------------------------------------------------------------------------
| airport | Airport_Name | location | X | Y |
==========================================================================================================================
| nas:MYEMairport | "Governors Harbour" | nas:MYEMcoordinates | "-76.330178"^^xsd:float | "25.283586"^^xsd:float |
| nas:MDPCairport | "Punta Cana Intl" | nas:MDPCcoordinates | "-68.366186"^^xsd:float | "18.570781"^^xsd:float |
| nas:MUGTairport | "Mariana Grajales" | nas:MUGTcoordinates | "-75.158333"^^xsd:float | "20.085278"^^xsd:float |
| nas:MDSTairport | "Cibao Intl" | nas:MDSTcoordinates | "-70.604689"^^xsd:float | "19.406092"^^xsd:float |
| nas:MYLSairport | "Stella Maris" | nas:MYLScoordinates | "-75.268778"^^xsd:float | "23.583047"^^xsd:float |
| nas:MBNCairport | "North Caicos" | nas:MBNCcoordinates | "-71.939658"^^xsd:float | "21.917486"^^xsd:float |
| nas:MUMOairport | "Orestes Acosta" | nas:MUMOcoordinates | "-74.922222"^^xsd:float | "20.653889"^^xsd:float |
| nas:MYRPairport | "New Port Nelson" | nas:MYRPcoordinates | "-74.836186"^^xsd:float | "23.684378"^^xsd:float |
| nas:MYEGairport | "George Town" | nas:MYEGcoordinates | "-75.781670"^^xsd:float | "23.466667"^^xsd:float |
| nas:MUBYairport | "Carlos Manuel De Cespedes" | nas:MUBYcoordinates | "-76.621389"^^xsd:float | "20.396389"^^xsd:float |
--------------------------------------------------------------------------------------------------------------------------
Note, the query uses the property path rdf:type/rdfs:subClassOf* which only works if you've also loaded the ontology (NAS.ttl). The property path is necessary because the instance data (airportInst.ttl) uses subclasses of nas:Airport like nas:InternationAirport or nas:CanadianAirport.