12.4 每日总结（学习HBase）

3小时

 

 

（1）      在终端打印出指定的表的所有记录数据；

import org.apache.hadoop.hive.conf.HiveConf;

import org.apache.hadoop.hive.jdbc.HiveStatement;

import org.apache.hadoop.hive.jdbc.HiveConnection;

 

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

 

public class HivePrintTableData {

    public static void main(String[] args) {

        String tableName = "your_table_name";

        String url = "jdbc:hive2://localhost:10000/default";

      String user = "hadoop";

        String pwd = "123456";

        String tableName = "t1 ";

 

        try (Connection con = DriverManager.getConnection(url, user, pwd);

             Statement stmt = con.createStatement()) {

            ResultSet res = stmt.executeQuery("SELECT * FROM " + tableName);

            while (res.next()) {

                // Assuming the table has two columns, adjust accordingly

                System.out.println(res.getString(1) + ", " + res.getString(2));

            }

        } catch (SQLException e) {

            e.printStackTrace();

        }

    }

}

 

（2）      向已经创建好的表添加和删除指定的列族或列；

 

 

import org.apache.hadoop.hive.jdbc.HiveStatement;

import org.apache.hadoop.hive.jdbc.HiveConnection;

 

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.SQLException;

import java.sql.Statement;

 

public class HiveAlterTable {

    public static void main(String[] args) {

        String url = "jdbc:hive2://localhost:10000/default";

        String user = "user";

        String pwd = "password";

        String tableName = "your_table_name";

        String columnName = "new_column";

        String columnType = "string";

 

        try (Connection con = DriverManager.getConnection(url, user, pwd);

             Statement stmt = con.createStatement()) {

            // Add column

            stmt.execute("ALTER TABLE " + tableName + " ADD COLUMNS (" + columnName + " " + columnType + ");");

            // Drop column

            stmt.execute("ALTER TABLE " + tableName + " DROP COLUMNS (" + columnName + ");");

        } catch (SQLException e) {

            e.printStackTrace();

        }

    }

}