本文介紹了SPARQL查詢是否重復(fù)我不理解的處理方法，對(duì)大家解決問(wèn)題具有一定的參考價(jià)值，需要的朋友們下面隨著小編來(lái)一起學(xué)習(xí)吧！
問(wèn)題描述
我使用此查詢獲取所有編程語(yǔ)言及其詳細(xì)信息。這是我的測(cè)試課。我在Java中使用過(guò)它，它工作得很好。我面臨的問(wèn)題是，有一種語(yǔ)言叫做”ML(編程語(yǔ)言)”
它以不同的摘要、不同的影響多次印刷。不僅是ML，還有一些其他語(yǔ)言也在做這件事。我不知道我的查詢中是否有任何問(wèn)題，或者它是否原樣獲取了準(zhǔn)確的數(shù)據(jù)。
package io.naztech.dbpedia;
import java.io.ByteArrayOutputStream;
import java.util.List;
import org.apache.jena.query.ResultSet;
import org.apache.jena.query.ResultSetFormatter;
import org.apache.jena.sparql.engine.http.QueryEngineHTTP;
import org.junit.BeforeClass;
import org.junit.Test;
import io.naztech.talent.model.PediaTag;
public class testDataFetching {
@Test
public void testAllDataFetching() {
String q = "PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
"+
"PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
"+
"PREFIX dbo: <http://dbpedia.org/ontology/>
"+
"PREFIX dbp: <http://dbpedia.org/property/>
"+
"PREFIX owl: <http://www.w3.org/2002/07/owl#>
"+
"PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
" +
"PREFIX foaf: <http://xmlns.com/foaf/0.1/>
" +
"PREFIX dc: <http://purl.org/dc/elements/1.1/>
" +
"PREFIX : <http://dbpedia.org/resource/>
" +
"PREFIX dbpedia2: <http://dbpedia.org/property/>
" +
"PREFIX dbpedia: <http://dbpedia.org/>
" +
"PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
" +
"SELECT DISTINCT ?pl ?pl_label ?abstract ?_thumbnail
" +
"( Group_concat ( DISTINCT ?_influenced_label; separator= ", ") AS ?influenced )
" +
"( Group_concat ( DISTINCT ?_influencedBy_label; separator= ", ") AS ?influencedBy )
" +
"( group_concat ( DISTINCT ?_sameAs; separator=", " ) AS ?sameAs )
" +
"( group_concat ( DISTINCT ?_paradigm_label; separator=", " ) AS ?paradigm )
" +
"WHERE {
" +
" ?pl rdf:type dbo:ProgrammingLanguage .
" +
" OPTIONAL { ?pl dbo:abstract ?abstract .
" +
" FILTER ( LANG ( ?abstract ) = 'en' ) . }
" +
" ?pl rdfs:label ?pl_label .
" +
" FILTER ( LANG ( ?pl_label ) = 'en' ) .
" +
" OPTIONAL { ?pl dbo:influenced ?_influenced .
" +
" ?_influenced rdfs:label ?_influenced_label .
" +
" FILTER ( LANG ( ?_influenced_label ) = 'en' ) . }
" +
" OPTIONAL { ?pl dbo:influencedBy ?_influencedBy .
" +
" ?_influencedBy rdfs:label ?_influencedBy_label .
" +
" FILTER ( LANG ( ?_influencedBy_label ) = 'en' ) . }
" +
" OPTIONAL { ?pl owl:sameAs ?_sameAs . }
" +
" OPTIONAL { ?pl dbp:paradigm ?_paradigm .
" +
" ?_paradigm rdfs:label ?_paradigm_label . }
" +
" OPTIONAL { ?pl dbo:thumbnail ?_thumbnail . }
" +
" }"+
" GROUP BY ?pl ?pl_label ?abstract ?_thumbnail ?influenced ?influencedBy ?sameAs ?paradigm";
@SuppressWarnings("resource")
QueryEngineHTTP queryEngine = new QueryEngineHTTP("http://live.dbpedia.org/sparql", q);
ResultSet results = queryEngine.execSelect();
int count = 0;
while (results.hasNext())
{
QuerySolution qs = results.next();
System.out.println("NAME-->
"+qs.get("pl_label").toString()+"
");
if(qs.get("influenced") != null)
{
System.out.println("INFLUENCED-->
"+qs.get("influenced").toString()+"
");
}
if(qs.get("influencedBy") != null)
{
System.out.println("INFLUENCED BY-->
"+qs.get("influencedBy").toString()+"
");
}
if(qs.get("abstract") != null)
{
System.out.println("ABSTRACT-->
"+qs.get("abstract").toString()+"
");
}
if(qs.get("sameAs") != null)
{
System.out.println("SAME AS-->
"+qs.get("sameAs").toString()+"
");
}
if(qs.get("paradigm") != null)
{
System.out.println("PARADIGM-->
"+qs.get("paradigm").toString()+"
");
}
if(qs.get("_thumbnail") != null)
{
System.out.println("THUMBNAIL-->
"+qs.get("_thumbnail").toString()+"
");
}
System.out.println("
");
count++;
}
System.out.println(count);
}
}
推薦答案
數(shù)據(jù)集中有3篇英文摘要，請(qǐng)看DBpedia Live resource。
您可以通過(guò)從group by ...部分中刪除?abstract變量來(lái)解決此問(wèn)題，而使用聚合函數(shù)(sample, min, max)來(lái)獲取任何抽象：
SELECT ?pl ?pl_label
(MIN(?_abstract) AS ?abstract) # <- used MIN here to ensure stable result
?_thumbnail
(GROUP_CONCAT(DISTINCT ?_influenced_label ; separator='; ') AS ?influenced)
(GROUP_CONCAT(DISTINCT ?_influencedBy_label ; separator='; ') AS ?influencedBy)
(GROUP_CONCAT(DISTINCT ?_sameAs ; separator=', ') AS ?sameAs)
(GROUP_CONCAT(DISTINCT ?_paradigm_label ; separator=', ') AS ?paradigm)
WHERE
{ ?pl a dbo:ProgrammingLanguage ;
rdfs:label ?pl_label
FILTER ( lang(?pl_label) = "en" )
OPTIONAL
{ ?pl dbo:abstract ?_abstract
FILTER ( lang(?_abstract) = "en" )
}
OPTIONAL
{ ?pl dbo:influenced/rdfs:label ?_influenced_label
FILTER ( lang(?_influenced_label) = "en" )
}
OPTIONAL
{ ?pl dbo:influencedBy/rdfs:label ?_influencedBy_label
FILTER ( lang(?_influencedBy_label) = "en" )
}
OPTIONAL
{ ?pl owl:sameAs ?_sameAs }
OPTIONAL
{ ?pl dbp:paradigm/rdfs:label ?_paradigm_label
FILTER ( lang(?_paradigm_label) = "en" )
}
OPTIONAL
{ ?pl dbo:thumbnail ?_thumbnail }
}
GROUP BY ?pl ?pl_label ?_thumbnail
更新
我在這里添加@TallTed的評(píng)論，他是Virtuoso背后的人之一，比我更了解：
請(qǐng)注意，雖然建議的聚合函數(shù)(<[2-3]、
MAX、
SAMPLE)將獲得值，不能保證
該值將是最新接收到數(shù)據(jù)集的值。
這篇關(guān)于SPARQL查詢是否重復(fù)我不理解的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，
