Apache IoTDB开发系统JDBC原生接口

举报
小云悠悠zZ 发表于 2023/10/07 09:02:40 2023/10/07
【摘要】 version 表示客户端使用的 SQL 语义版本,用于升级 0.13 时兼容 0.12 的 SQL 语义,可能取值有:V_0_12、V_0_13、V_1_0。

依赖

  • JDK >= 1.8
  • Maven >= 3.6

安装方法

在根目录下执行下面的命令:

  1. mvn clean install -pl jdbc -am -Dmaven.test.skip=true

在 MAVEN 中使用 IoTDB JDBC

  1. <dependencies>
  2. <dependency>
  3. <groupId>org.apache.iotdb</groupId>
  4. <artifactId>iotdb-jdbc</artifactId>
  5. <version>1.0.0</version>
  6. </dependency>
  7. </dependencies>

示例代码

本章提供了如何建立数据库连接、执行 SQL 和显示查询结果的示例。

要求您已经在工程中包含了数据库编程所需引入的包和 JDBC class.

注意:为了更快地插入,建议使用 executeBatch()

import java.sql.*;
import org.apache.iotdb.jdbc.IoTDBSQLException;
public class JDBCExample {
  /**
   * Before executing a SQL statement with a Statement object, you need to create a Statement object using the createStatement() method of the Connection object.
   * After creating a Statement object, you can use its execute() method to execute a SQL statement
   * Finally, remember to close the 'statement' and 'connection' objects by using their close() method
   * For statements with query results, we can use the getResultSet() method of the Statement object to get the result set.
   */
  public static void main(String[] args) throws SQLException {
    Connection connection = getConnection();
    if (connection == null) {
      System.out.println("get connection defeat");
      return;
    }
    Statement statement = connection.createStatement();
    //Create database
    try {
      statement.execute("CREATE DATABASE root.demo");
    }catch (IoTDBSQLException e){
      System.out.println(e.getMessage());
    }
    //SHOW DATABASES
    statement.execute("SHOW DATABASES");
    outputResult(statement.getResultSet());
    //Create time series
    //Different data type has different encoding methods. Here use INT32 as an example
    try {
      statement.execute("CREATE TIMESERIES root.demo.s0 WITH DATATYPE=INT32,ENCODING=RLE;");
    }catch (IoTDBSQLException e){
      System.out.println(e.getMessage());
    }
    //Show time series
    statement.execute("SHOW TIMESERIES root.demo");
    outputResult(statement.getResultSet());
    //Show devices
    statement.execute("SHOW DEVICES");
    outputResult(statement.getResultSet());
    //Count time series
    statement.execute("COUNT TIMESERIES root");
    outputResult(statement.getResultSet());
    //Count nodes at the given level
    statement.execute("COUNT NODES root LEVEL=3");
    outputResult(statement.getResultSet());
    //Count timeseries group by each node at the given level
    statement.execute("COUNT TIMESERIES root GROUP BY LEVEL=3");
    outputResult(statement.getResultSet());
    //Execute insert statements in batch
    statement.addBatch("insert into root.demo(timestamp,s0) values(1,1);");
    statement.addBatch("insert into root.demo(timestamp,s0) values(2,15);");
    statement.addBatch("insert into root.demo(timestamp,s0) values(2,17);");
    statement.addBatch("insert into root.demo(timestamp,s0) values(4,12);");
    statement.executeBatch();
    statement.clearBatch();
    //Full query statement
    String sql = "select * from root.demo";
    ResultSet resultSet = statement.executeQuery(sql);
    System.out.println("sql: " + sql);
    outputResult(resultSet);
    //Exact query statement
    sql = "select s0 from root.demo where time = 4;";
    resultSet= statement.executeQuery(sql);
    System.out.println("sql: " + sql);
    outputResult(resultSet);
    //Time range query
    sql = "select s0 from root.demo where time >= 2 and time < 5;";
    resultSet = statement.executeQuery(sql);
    System.out.println("sql: " + sql);
    outputResult(resultSet);
    //Aggregate query
    sql = "select count(s0) from root.demo;";
    resultSet = statement.executeQuery(sql);
    System.out.println("sql: " + sql);
    outputResult(resultSet);
    //Delete time series
    statement.execute("delete timeseries root.demo.s0");
    //close connection
    statement.close();
    connection.close();
  }
  public static Connection getConnection() {
    // JDBC driver name and database URL
    String driver = "org.apache.iotdb.jdbc.IoTDBDriver";
    String url = "jdbc:iotdb://127.0.0.1:6667/";
    // set rpc compress mode
    // String url = "jdbc:iotdb://127.0.0.1:6667?rpc_compress=true";
    // Database credentials
    String username = "root";
    String password = "root";
    Connection connection = null;
    try {
      Class.forName(driver);
      connection = DriverManager.getConnection(url, username, password);
    } catch (ClassNotFoundException e) {
      e.printStackTrace();
    } catch (SQLException e) {
      e.printStackTrace();
    }
    return connection;
  }
  /**
   * This is an example of outputting the results in the ResultSet
   */
  private static void outputResult(ResultSet resultSet) throws SQLException {
    if (resultSet != null) {
      System.out.println("--------------------------");
      final ResultSetMetaData metaData = resultSet.getMetaData();
      final int columnCount = metaData.getColumnCount();
      for (int i = 0; i < columnCount; i++) {
        System.out.print(metaData.getColumnLabel(i + 1) + " ");
      }
      System.out.println();
      while (resultSet.next()) {
        for (int i = 1; ; i++) {
          System.out.print(resultSet.getString(i));
          if (i < columnCount) {
            System.out.print(", ");
          } else {
            System.out.println();
            break;
          }
        }
      }
      System.out.println("--------------------------\n");
    }
  }
}
  1. 可以在 url 中指定 version 参数:
  1. String url = "jdbc:iotdb://127.0.0.1:6667?version=V_1_0";

version 表示客户端使用的 SQL 语义版本,用于升级 0.13 时兼容 0.12 的 SQL 语义,可能取值有:V_0_12V_0_13V_1_0

【版权声明】本文为华为云社区用户原创内容,转载时必须标注文章的来源(华为云社区)、文章链接、文章作者等基本信息, 否则作者和本社区有权追究责任。如果您发现本社区中有涉嫌抄袭的内容,欢迎发送邮件进行举报,并提供相关证据,一经查实,本社区将立刻删除涉嫌侵权内容,举报邮箱: cloudbbs@huaweicloud.com
  • 点赞
  • 收藏
  • 关注作者

评论(0

0/1000
抱歉,系统识别当前为高风险访问,暂不支持该操作

全部回复

上滑加载中

设置昵称

在此一键设置昵称,即可参与社区互动!

*长度不超过10个汉字或20个英文字符,设置后3个月内不可修改。

*长度不超过10个汉字或20个英文字符,设置后3个月内不可修改。