Dbpedia, optional tag trouble - sparql

Question

I'm having trouble getting the optional tag to return rows where some attributes may not exist. For example in the following query I return some information about the MMA fighter Lyoto Machida http://goo.gl/cWFk9N
SELECT ?surname ?givenName ?nick ?height ?born ?nationality ?birthplace
where {
<http://dbpedia.org/resource/Lyoto_Machida>
foaf:surname ?surname ;
foaf:givenName ?givenName ;
dbp:otherNames ?nick ;
dbo:height ?height ;
dbp:birthDate ?born ;
dbp:nationality ?nationality ;
dbp:birthPlace ?birthplace
}
Now if I want to use that same query, except with the MMA fighter Luke Rockhold I get no results. This is because he does not have a listed nationality or otherNames. So I tried using the optional tags around all my attributes but this still didn't work.
SELECT ?surname ?givenName ?nick ?height ?born ?nationality ?birthplace
where {
<http://dbpedia.org/resource/Luke_Rockhold>
OPTIONAL {foaf:surname ?surname ;}
OPTIONAL {foaf:givenName ?givenName ;}
OPTIONAL {dbp:otherNames ?nick ;}
OPTIONAL {dbo:height ?height ;}
OPTIONAL {dbp:birthDate ?born ;}
OPTIONAL {dbp:nationality ?nationality ; }
OPTIONAL {dbp:birthPlace ?birthplace }
}
Is there an error with my syntax or logic? I'm quite new to using sparql and dbpedia, any help is greatly appreciated

Answer 1

You can't split a single pattern with OPTIONAL like that. The parts outside and inside OPTIONAL have to be valid patterns on their own. One way to do this would be to use BIND:
SELECT ?surname ?givenName ?nick ?height ?born ?nationality ?birthplace
WHERE {
BIND(:Luke_Rockhold AS ?x)
OPTIONAL {?x foaf:surname ?surname}
OPTIONAL {?x foaf:givenName ?givenName}
OPTIONAL {?x dbp:otherNames ?nick}
OPTIONAL {?x dbo:height ?height}
OPTIONAL {?x dbp:birthDate ?born}
OPTIONAL {?x dbp:nationality ?nationality}
OPTIONAL {?x dbp:birthPlace ?birthplace}
}