一个SPARQL（有效）查询与另一个（无效）查询之间的区别 [英] Difference between one SPARQL (working) query and another one (not working)

问题描述

我想从以下页面获取得分手（ marcatori ）： http： ///。it.dbpedia.org/resource/Modena_Football_Club_1962-1963 使用以下SPARQL端点： http://uriburner.com/sparql/

I want to get the scorers (marcatori) from this page: http://it.dbpedia.org/resource/Modena_Football_Club_1962-1963 using this SPARQL endpoint: http://uriburner.com/sparql/

如果我使用此查询：

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT DISTINCT
  ?team
  ?club
  (group_concat(distinct ?scorer;separator=";;;") as ?scorers) 
WHERE {
SERVICE <http://it.dbpedia.org/sparql/> {
   ?value rdfs:label "Campionato italiano di calcio Serie A"@it .
   ?year <http://purl.org/dc/terms/subject> ?value . 
   ?team <http://dbpedia.org/ontology/league> ?year .
   ?team <http://it.dbpedia.org/property/club> ?club .
   OPTIONAL { ?team <http://it.dbpedia.org/property/marcatori> ?scorer 
   }
}

} 
GROUP BY ?team ?club 
ORDER BY ?club
LIMIT 1 

我没有得到任何结果，就像我使用该结果一样：

I get no results, where as if I use this one:

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT DISTINCT
  ?team
  ?club
WHERE {
SERVICE <http://it.dbpedia.org/sparql/> {
   ?value rdfs:label "Campionato italiano di calcio Serie A"@it .
   ?year <http://purl.org/dc/terms/subject> ?value . 
   ?team <http://dbpedia.org/ontology/league> ?year .
   ?team <http://it.dbpedia.org/property/club> ?club 
}

} 
GROUP BY ?team ?club 
ORDER BY ?club
LIMIT 1 

我正确地得到：

{ "head": { "link": [], "vars": ["team", "club"] },
  "results": { "distinct": false, "ordered": true, "bindings": [
    { "team": { "type": "uri", "value": 
 "http://it.dbpedia.org/resource/Modena_Football_Club_1962-1963" }  , 
 "club": { "type": "uri", "value": 
 "http://it.dbpedia.org/resource/Modena_Football_Club" }} ] } }

有人知道为什么第一个查询返回空吗？

Does anyone know why the first query returns empty?

推荐答案

您可以替换

（group_concat（distinct？scorer; separator = ;;;）作为？scorers）

与

sql：group_concat（？scorer， ;;;）as？scorers

在 http://it.dbpedia.org/sparql ，不确定为什么需要URI刻录机。

This should work fine on http://it.dbpedia.org/sparql, not sure why you need URI burner.

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