这个 SPARQL 查询有什么问题？
String sparql = "";
sparql+= "PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>\n";
sparql+= "PREFIX i: <http://evolizer.org/ontologies/seon/2010/09/softwaremetrics.owl#>\n";
sparql+= "PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>\n";
sparql+="SELECT ?metric ?value\n";
sparql+="WHERE {\n";
sparql+="?metric rdf:type i:SoftwareDesignMetric .\n";
sparql+="?metric i:hasName McCabe .\n";
sparql+= "?metric i:hasValue ?value \n";
sparql+="}\n";
通过执行我得到这个异常：
A first chance exception of type 'System.Net.WebException' occurred in System.dll
exception when sending query:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX i: <http://evolizer.org/ontologies/seon/2010/09/softwaremetrics.owl#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT ?metric ?value
WHERE {
?metric rdf:type i:SoftwareDesignMetric .
?metric i:hasName McCabe .
?metric i:hasValue ?value
}
问题必须是查询本身，因为对同一服务器的其他查询正在工作。
String sparql = "";
sparql+= "PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>\n";
sparql+= "PREFIX i: <http://evolizer.org/ontologies/seon/2010/09/softwaremetrics.owl#>\n";
sparql+= "PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>\n";
sparql+="SELECT ?metric ?value\n";
sparql+="WHERE {\n";
sparql+="?metric rdf:type i:SoftwareDesignMetric .\n";
sparql+="?metric i:hasName McCabe .\n";
sparql+= "?metric i:hasValue ?value \n";
sparql+="}\n";
By executing i get this exception:
A first chance exception of type 'System.Net.WebException' occurred in System.dll
exception when sending query:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX i: <http://evolizer.org/ontologies/seon/2010/09/softwaremetrics.owl#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT ?metric ?value
WHERE {
?metric rdf:type i:SoftwareDesignMetric .
?metric i:hasName McCabe .
?metric i:hasValue ?value
}
The problem has to be the query itself, because other queries to the same server are working.
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所有示例此处都放置字符串参数（例如示例中的 McCabe）用引号引起来。会是这样吗？
All of the examples here place the string arguments (such as McCabe in your example) in quotes. Could this be it?
我还找到了一个验证器，它提示查询有什么问题：
http://sparql.org/query -validator.html
I also found a validator that gives hint on what is wrong with a query:
http://sparql.org/query-validator.html