Implementing Neo4j aggregate queries using Java
To implement various aggregation queries for Neo4j using Java, it is first necessary to add Neo4j's driver dependencies in the project. Neo4j provides the official Java driver and can add the following dependencies through Maven:
<dependencies>
<dependency>
<groupId>org.neo4j.driver</groupId>
<artifactId>neo4j-java-driver</artifactId>
<version>4.3.7</version>
</dependency>
</dependencies>
Then, you can use the following Java code to implement various data aggregation queries:
1. Count query
import org.neo4j.driver.*;
import static org.neo4j.driver.Values.parameters;
public class CountQueryExample {
public static void main(String[] args) {
try (Driver driver = GraphDatabase.driver("bolt://localhost:7687", AuthTokens.basic("username", "password"));
Session session = driver.session()) {
String query = "MATCH (n:Person) RETURN count(n) AS count";
Result result = session.run(query);
while (result.hasNext()) {
Record record = result.next();
System.out.println(record.get("count").asInt());
}
}
}
}
2. Maximum value query
import org.neo4j.driver.*;
import static org.neo4j.driver.Values.parameters;
public class MaxQueryExample {
public static void main(String[] args) {
try (Driver driver = GraphDatabase.driver("bolt://localhost:7687", AuthTokens.basic("username", "password"));
Session session = driver.session()) {
String query = "MATCH (n:Person) RETURN max(n.age) AS maxAge";
Result result = session.run(query);
while (result.hasNext()) {
Record record = result.next();
System.out.println(record.get("maxAge").asInt());
}
}
}
}
3. Average value query
import org.neo4j.driver.*;
import static org.neo4j.driver.Values.parameters;
public class AverageQueryExample {
public static void main(String[] args) {
try (Driver driver = GraphDatabase.driver("bolt://localhost:7687", AuthTokens.basic("username", "password"));
Session session = driver.session()) {
String query = "MATCH (n:Person) RETURN avg(n.age) AS averageAge";
Result result = session.run(query);
while (result.hasNext()) {
Record record = result.next();
System.out.println(record.get("averageAge").asDouble());
}
}
}
}
4. Sum query
import org.neo4j.driver.*;
import static org.neo4j.driver.Values.parameters;
public class SumQueryExample {
public static void main(String[] args) {
try (Driver driver = GraphDatabase.driver("bolt://localhost:7687", AuthTokens.basic("username", "password"));
Session session = driver.session()) {
String query = "MATCH (n:Person) RETURN sum(n.age) AS totalAge";
Result result = session.run(query);
while (result.hasNext()) {
Record record = result.next();
System.out.println(record.get("totalAge").asInt());
}
}
}
}
These sample codes demonstrate how to use Java to implement various aggregate queries for Neo4j. You can modify these codes according to your own needs and connect according to the actual Neo4j database configuration. Remember to replace the placeholders in the code with the correct username and password.
