Optional Pattern
SELECT ?cat ?val ?uri
WHERE { ?x rdf:value ?val. ?x category ?cat.
OPTIONAL ?al contains ?x. ?al linkTo ?uri. }
- Returns:
["Total Members",100,Res],…,
- But also:
["Full Members",20, ],…,
- (note the empty return value!)
118 (147)
SELECT ?cat ?val ?uri
WHERE { ?x rdf:value ?val. ?x category ?cat.
OPTIONAL ?al contains ?x. ?al linkTo ?uri. }
["Total Members",100,Res],…,
["Full Members",20, ],…,