用SPARQL选择依赖树上的连接顶点并按深度排序”

首先，定义一个变量，列出所有连接到给定节点的子节点：

PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT DISTINCT ?node ?child WHERE {
  { 
    ?node foaf:name "given_node_name" .
  } UNION {
    ?child foaf:name "given_node_name" .
    ?node ?p ?child .
  }
}

接下来，计算每个子节点的深度：

PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT DISTINCT ?child (count(?node)-1 AS ?depth) WHERE {
  { 
    ?node foaf:name "given_node_name" .
  } UNION {
    ?child foaf:name "given_node_name" .
    ?node ?p ?child .
  }
  { 
    ?node foaf:name "given_node_name" .
  } UNION {
    ?child foaf:name "given_node_name" .
    ?node ?p ?child .
  }
} GROUP BY ?child

最后，按深度顺序对子节点进行排序：

PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT DISTINCT ?child WHERE {
  { 
    ?node foaf:name "given_node_name" .
  } UNION {
    ?child foaf:name "given_node_name" .
    ?node ?p ?child .
  }
  { 
    ?node foaf:name "given_node_name" .
  } UNION {
    ?child foaf:name "given_node_name" .
    ?node ?p ?child .
  }
  { 
    ?child foaf:name "given_node_name" .
    ?depth_uri rdf:value ?depth .
  } BIND(str(?depth) as ?depth_str) 
} ORDER BY xsd:integer(?depth_str)