在Java應用程序中對Neo4j的查詢

Question

我正在使用Java應用程序中的Neo4j。如何統計數據庫中的所有節點並在屏幕上打印？誰能幫我？

package pesquisaBanco; 

import org.neo4j.graphdb.GraphDatabaseService; 
//import org.neo4j.graphdb.Node; 
import org.neo4j.graphdb.Transaction; 
import org.neo4j.graphdb.factory.GraphDatabaseFactory; 

public class pesquisar { 

    public static void main(String[] args) { 
     // TODO Auto-generated method stub 

     GraphDatabaseService graphDb = new GraphDatabaseFactory() 
       .newEmbeddedDatabase("C:/Users/Jessica/neo4j"); 
     Transaction transaction; 
     transaction = graphDb.beginTx(); 

     //QUERY HERE! 

     transaction.success(); 
     transaction.close(); 

    } 

} 

Answer 1

你可以用暗號COUNT aggregation function查詢： MATCH n RETURN count(n) AS count。

由AS定義的別名就是爲了使columnAs更易於使用。

請注意，最好的做法是在try-with-resources塊以將事務，如：

ExecutionEngine engine = new ExecutionEngine(graphDb); 
try (Transaction transaction= graphDb.beginTx(); 
    ResourceIterator<Long> results = engine.execute("MATCH n RETURN count(n) AS count").columnAs("count")) { 

    System.out.println(results.next()); 
    transaction.success(); 
}