jena-sdb/testing/Optionals1/opt-4.rq

# single triple pattern, block optional 
PREFIX : <http://example/>

SELECT * WHERE
{ 
{
    ?x :p 1 .
    OPTIONAL { ?x :pZZZ ?a . ?a :q1 ?v .}   # Term not in data
}
UNION
{
    ?x :p "abc" .
}

}