SPARQL：如何结合两个主题在 CONSTRUCT 中使用？

Question

我正在编写一个 SPARQL 查询，其中我正在创建一个 RDF 图。我正在使用 SPARQL 构造。作为我工作的要求，我必须连接两个主题值并将其与 CONSTRUCT 语句一起使用。我尝试过以下操作（我的 RDF 图在 Virtuoso 中）：

prefix map: <#> 
prefix db: <> 
prefix vocab: <vocab/> 
prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> 
prefix xsd: <http://www.w3.org/2001/XMLSchema#> 
prefix d2rq: <http://www.wiwiss.fu-berlin.de/suhl/bizer/D2RQ/0.1#> 
prefix jdbc: <http://d2rq.org/terms/jdbc/>
prefix fn: <http://www.w3.org/2005/xpath-functions#> 

CONSTRUCT {
?p1 a d2rq:ClassMap
}

FROM <http://www.ndssl.bi.vt.edu/fuse>
WHERE 
{ 
<http://www.ndssl.bi.vt.edu/fuse#DataSource> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#Class>.
<http://www.ndssl.bi.vt.edu/fuse#OracleDataSource>  <http://www.w3.org/2000/01/rdf-schema#subClassOf> <http://www.ndssl.bi.vt.edu/fuse#DataSource>.
?DB <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>   <http://www.ndssl.bi.vt.edu/fuse#OracleDataSource>.
<http://www.ndssl.bi.vt.edu/fuse#HouseholdsWithinAdminRegion> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#Class>.
?Table <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>   <http://www.ndssl.bi.vt.edu/fuse#HouseholdsWithinAdminRegion>.
BIND(CONCAT(?DB, ?Table) AS ?p1)
}

但是，我收到以下错误：

Virtuoso RDF01 Error Bad variable value in CONSTRUCT: "http://www.ndssl.bi.vt.edu/fuse#PROTOPOPhttp://www.ndssl.bi.vt.edu/fuse#MIAMI_HOUSEHOLD_2009_1" (tag 246 box flags 0) is not a valid subject, only object of a triple can be a literal

请告诉我如何解决。

Answer 1

该错误基本上是说您正在连接两个 URI：

http://www.ndssl.bi.vt.edu/fuse#PROTOPOP
http://www.ndssl.bi.vt.edu/fuse#MIAMI_HOUSEHOLD_2009_1

变成文字。我不知道你到底想做什么，但你真的想连接整个 URI 还是只连接 # 之后的最后一部分？如果你想在# 之后连接你需要省略命名空间。

bind (concat(strafter(str(?s),str(fuse:)), strafter(str(?o),str(fuse:))) as ?p)

即使在这个阶段，绑定的结果也是 literal，您需要将其转换为 URI。

bind (uri(concat(strafter(str(?s),str(fuse:)), strafter(str(?o),str(fuse:)))) as ?p)

通常我会大大简化您的查询：

prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> 
prefix fuse: <http://www.ndssl.bi.vt.edu/fuse#>
prefix owl:<http://www.w3.org/2002/07/owl#>

CONSTRUCT {
    ?p1 a d2rq:ClassMap
}

FROM <http://www.ndssl.bi.vt.edu/fuse>
WHERE 
{ 
    fuse:DataSource a owl:Class.
    fuse:OracleDataSource  rdfs:subClassOf fuse:DataSource.
    ?DB a   fuse:DataSource.
    fuse:HouseholdsWithinAdminRegion a owl:Class.
    ?Table a  fuse:HouseholdsWithinAdminRegion.

    bind (uri(concat(strafter(str(?DB),str(fuse:)), 
        strafter(str(?Table),str(fuse:)))) as ?p)
}