import java.sql.*;

import java.util.Scanner;

public class Test_4 {

    public static void main(String[] args) {

        // 1.加载JDBC驱动程序

        try {

            Class.forName("com.mysql.jdbc.Driver");

        } catch (ClassNotFoundException e) {

            e.printStackTrace();

        }

        // 2.创建数据库的链接

        try {

            System.out.println("连接数据库...");

            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/stu", "root", "dai324542");

            // 3.执行SQL语句

            Statement sql = con.createStatement();// Statement接口

            ResultSet re = sql.executeQuery("select * from t_student");// executeQuery查询----ResultSet结果集

            // 4.接收并处理结果集

            System.out.println("    查询中.....");

            while (re.next()) {

                int id = re.getInt("id");

                String name = re.getString("name");

                String classes = re.getString("classes");

                // 输出数据

                System.out.println("学号: " + id);

                System.out.println("姓名: " + name);

                System.out.println("班级: " + classes);

                System.out.print("\n");

            }

            Scanner reader = new Scanner(System.in);

            System.out.println("please input id: ");

            int Id = reader.nextInt();

            ResultSet rs = sql.executeQuery("select * from t_student where id='" + Id + "'");

            if (rs.next()) {

                System.out.println("please input new name: ");

                String newname = reader.next();

                int n = sql.executeUpdate("update t_student set name='" + newname + "'where id='" + Id + "'");

                if (n > 0) {

                    System.out.println("success!");

                } else {

                    System.out.println("修改失败!");

                }

            } else {

                System.out.println("未查询到此id!");

            }

            // 5.断开连接，关闭数据库

            re.close();

            con.close();

        } catch (

        SQLException e) {

            e.printStackTrace();

        }

    }

}