[JDBC] Android creates a mysql connection to perform regular operations of adding, deleting and modifying the database

This article introduces how Android connects to the mysql database to implement add, delete, modify and query operations.

Recommended related mysql video tutorials: "mysql tutorial"

The code is available for debugging by myself, you can refer to it.

The code is as follows:

package com.web.redrain;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import android.app.Activity;
import android.os.Bundle;
public class JDBC_Test extends Activity {
    // 创建静态全局变量
    static Connection conn;
    static Statement st;
    public void onCreate(Bundle savedInstanceState){
     super.onCreate(savedInstanceState);
     setContentView(R.layout.sound);
     insert();    //插入添加记录
      update();    //更新记录数据
      //   delete();    //删除记录
       //  query();
    }
    /* 插入数据记录，并输出插入的数据记录数*/
    public static void insert() {
        conn = getConnection();    // 首先要获取连接，即连接到数据库
       try {
            String sql = "INSERT INTO tb_user(username)"+ " VALUES ('Tom1')";    // 插入数据的sql语
            st = (Statement) conn.createStatement();    // 创建用于执行静态sql语句的Statement对象
            int count = st.executeUpdate(sql);    // 执行插入操作的sql语句，并返回插入数据的个
           System.out.println("向tb_user表中插入 " + count + " 条数据");    //输出插入操作的处理结果
             conn.close();    //关闭数据库连接
        } catch (SQLException e) {
            System.out.println("插入数据失败" + e.getMessage());
        }
    }
    /* 更新符合要求的记录，并返回更新的记录数目*/
    public static void update() {
        conn = getConnection();    //同样先要获取连接，即连接到数据库
       try {
               String sql = "update tb_user set username='见人' where username = 'Tom1'";// 更新数据的sql语句
               st = (Statement) conn.createStatement();    //创建用于执行静态sql语句的Statement对象，st属局部变量
               int count = st.executeUpdate(sql);// 执行更新操作的sql语句，返回更新数据的个数
               System.out.println("tb_user表中更新 " + count + " 条数据");        //输出更新操作的处理结果
               conn.close();    //关闭数据库连接
        } catch (SQLException e) {
                System.out.println("更新数据失败");
        }
     }
    /* 查询数据库，输出符合要求的记录的情况*/
     public static void query() {
        conn = getConnection();    //同样先要获取连接，即连接到数据库
        try {
                String sql = "select * from tb_user";        // 查询数据的sql语句
              st = (Statement) conn.createStatement();    //创建用于执行静态sql语句的Statement对象，st属局部变量
                 ResultSet rs = st.executeQuery(sql);    //执行sql查询语句，返回查询数据的结果集
              System.out.println("最后的查询结果为：");
                while (rs.next()) // 判断是否还有下一个数据
                  {
                   // 根据字段名获取相应的值
                 String name = rs.getString("username");
                    String sex = rs.getString("sex");
                    String question = rs.getString("question");
                    String answer = rs.getString("answer");
                    String email = rs.getString("email");
                    //输出查到的记录的各个字段的值
                  System.out.println(name + " " + sex + " " + question+ " " + answer + " " + email );
                }
               conn.close();    //关闭数据库连接
         } catch (SQLException e) {
                System.out.println("查询数据失败");
        }
    }
    /* 删除符合要求的记录，输出情况*/
    public static void delete() {
        conn = getConnection();    //同样先要获取连接，即连接到数据库
      try {
               String sql = "delete from tb_user where username = 'dd'";// 删除数据的sql语句
               st = (Statement) conn.createStatement();    //创建用于执行静态sql语句的Statement对象，st属局部变量
               int count = st.executeUpdate(sql);// 执行sql删除语句，返回删除数据的数量
                System.out.println("tb_user表中删除 " + count + " 条数据\n");    //输出删除操作的处理结果    
                conn.close();    //关闭数据库连接
        } catch (SQLException e) {
               System.out.println("删除数据失败");
         }
    }
    /* 获取数据库连接的函数*/
    public static Connection getConnection() {
         Connection con = null;    //创建用于连接数据库的Connection对象
      try {
                Class.forName("com.mysql.jdbc.Driver");// 加载Mysql数据驱动
                con = DriverManager.getConnection("jdbc:mysql://数据库ip:3306/数据库名称", "数据库用户名", "数据库密码");// 创建数据连接
         } catch (Exception e) {
                 System.out.println("数据库连接失败" + e.getMessage());
        }
        return con;    //返回所建立的数据库连接
   }
}

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