web第三次课后作业--基于JDBC对mysql数据库的增删查改操作

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 blocke.printStackTrace();}}
}