一、工程搭建步骤

1.新建java项目，添加jdbc依赖
2.写java程序
3.添加mysql数据源，连接本地数据库
4.运行程序

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二、运行结果

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三、代码

代码解析

1. 加载数据驱动

try {
    Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
    e.printStackTrace();
}

2. demo是数据库名称，注意替换

try (Connection c = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/demo?useSSL=false&characterEncoding=UTF-8&allowPublicKeyRetrieval=true", "root", "1234");
)

3. executeUpdate()对数据库进行增加、删除操作；
   executeUpdate(*对数据库进行查询操作；
   getString(2)获取该元组第二列字段值.

ResultSet r = s.executeUpdate(sql);
ResultSet r = s.executeQuery(sql);
rs.getString(2)

完整代码

package catt;
import java.sql.*;

public class cat_1 {
    public static void main(String[] args) {

        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }

        try (Connection c = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/demo?useSSL=false&characterEncoding=UTF-8&allowPublicKeyRetrieval=true",
                "root", "1234");
             Statement s = c.createStatement();
        ){
            int r;

            //查询结果为多条的显示
            String sql = "select * from demo_cat_information";
            ResultSet rs = s.executeQuery(sql);
            while (rs.next()) {
                System.out.println("昵称:" + rs.getString(2)+" "+"性别："+ rs.getString(3)+" "+"年龄："+rs.getString(4));
            }
            //删除id=1的元组
            int id=1;//一定要确保id=1在数据库库中是存在的。
            String sql_1 = "delete from demo_cat_information where id = "+id;
            r = s.executeUpdate(sql_1);
            System.out.println("成功删除"+r+"条");

            //插入一个元组
            int id_1 = 5;
            String name = "歪胡子";
            String sex = "公";
            int age = 3;
            String sql_2 = "insert into demo_cat_information(id, name, sex, age) values (" + id_1 + ", '" + name + "', '" + sex + "', " + age + ")";
            r = s.executeUpdate(sql_2);
            System.out.println("成功添加" + r + "条");

            //修改一个索引名称
            String sql_update_id = "UPDATE demo_cat_information SET id = 1 WHERE id = 5";
            r = s.executeUpdate(sql_update_id);
            System.out.println("成功将id=5改为id=1，受影响行数：" + r);


        }catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}