[英]How to write a sparql query with variable predicate?
請看下面的例子:
@prefix : <#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
:Bob :score :78 .
:John :score :50 .
:rule1 :condition [
rdf:subject :score ;
rdf:predicate :notLessThan ;
rdf:object 60
];
:condition [
rdf:subject :score ;
rdf:predicate :notGreaterThan ;
rdf:object 80
];
:rating :passed .
:rule2 :condition [
rdf:subject :score ;
rdf:predicate :lessThan ;
rdf:object 60
];
:rating :failed .
我想通過 spqrql 查詢得到以下 output:
:Bob :rating :passed.
:John :rating :failed.
這里 rdf:predicate 可由用戶更改,其值可能是:
lessThan, notLessThan, greaterThan, notGreaterThan
那么如何基於動態謂詞編寫這個 SPARQL 語句呢?
我沒有任何想法。 感謝你們對我的幫助。
這看起來應該可以工作。
PREFIX : <#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
CONSTRUCT {
?student :rating ?rating .
} WHERE {
?student :score ?score .
?rule :rating ?rating .
OPTIONAL {
?rule :condition ?condition .
?condition rdf:subject :score .
?condition rdf:predicate ?predicate .
?condition rdf:object ?object .
# fails condition
FILTER (
! ( (?predicate = :lessThan && ?score < ?object ) ||
(?predicate = :notLessThan && ?score >= ?object ) ||
(?predicate = :greaterThan && ?score > ?object ) ||
(?predicate = :notGreaterThan && ?score <= ?object )
)
)
}
FILTER(!bound(?condition))
}
但我得到的只是“失敗”的結果。 讓我仔細看看出了什么問題。
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