JDBC+ORM 增删改查 MySQL

       

目录

一、数据库

二、封装Animal类

 三、增

四、删

五、改

六、查

 七、细节过程都在注释里

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        所谓ORM，即Object Relational Mapping。由于从数据库查询到的结果集（ResultSet）在进行遍历时，逐行遍历，然后一个字段一个字段的读取数据，取出的都是零散的数据，然后将零散数据一个一个输出，这样比较麻烦，不利于操作。所以在实际应用开发中，我们需要将零散的数据进行封装整理。

一、数据库

CREATE TABLE Animal(
aid INT(10) PRIMARY KEY AUTO_INCREMENT,
`name` VARCHAR(10) NOT NULL,
age INT(2),
num VARCHAR(10) NOT NULL UNIQUE,
birthday DATE NOT NULL );

INSERT INTO Animal VALUES(1001,'花小猫',2,'10001','2021-1-2');
INSERT INTO Animal VALUES(NULL,'壮小狗',3,'10002','2020-11-22');
INSERT INTO Animal VALUES(NULL,'皮小鼠',1,'10003','2022-3-18');

二、封装Animal类

        

package com.bdqn.animal;

import java.sql.Date;

public class Animal {
    /*
    aid INT(10) PRIMARY KEY AUTO_INCREMENT,
    `name` VARCHAR(10) NOT NULL,
    age INT(2),
    num VARCHAR(10) NOT NULL UNIQUE,
    birthday DATE NOT NULL );
    */

    private int aid;
    private String name;
    private int age;
    private String num;
    private Date birthday;


    public Animal() {
    }

    public Animal(int aid, String name, int age, String num, Date birthday) {
        this.aid = aid;
        this.name = name;
        this.age = age;
        this.num = num;
        this.birthday = birthday;
    }

    /**
     * 获取
     * @return aid
     */
    public int getAid() {
        return aid;
    }

    /**
     * 设置
     * @param aid
     */
    public void setAid(int aid) {
        this.aid = aid;
    }

    /**
     * 获取
     * @return name
     */
    public String getName() {
        return name;
    }

    /**
     * 设置
     * @param name
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * 获取
     * @return age
     */
    public int getAge() {
        return age;
    }

    /**
     * 设置
     * @param age
     */
    public void setAge(int age) {
        this.age = age;
    }

    /**
     * 获取
     * @return num
     */
    public String getNum() {
        return num;
    }

    /**
     * 设置
     * @param num
     */
    public void setNum(String num) {
        this.num = num;
    }

    /**
     * 获取
     * @return birthday
     */
    public Date getBirthday() {
        return birthday;
    }

    /**
     * 设置
     * @param birthday
     */
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String toString() {
        return "Animal{aid = " + aid + ", name = " + name + ", age = " + age + ", num = " + num + ", birthday = " + birthday + "}";
    }
}

 三、增

package com.bdqn.animal;

import java.sql.*;
import java.util.Calendar;

public class Insert {
    public static void main(String[] args) {
        // 1.加载驱动
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        }

        // 2.准备工作
        String url = "jdbc:mysql://127.0.0.1:3306/jdbcdatabase";//localhost也可写成127.0.0.1，jdbcdatabase为数据库名
        String user = "root";//登录数据库系统账号
        String password = "123456";//登录数据库密码
        // animal对象需要一个SQL的日期
        Calendar calendar = Calendar.getInstance();
        calendar.set(2021, Calendar.APRIL,5);
        // sql类型的Date()需要参数为long的时间戳
        long timeInMillis = calendar.getTimeInMillis();
        // 创建Animal对象
        Animal animal = new Animal(1004, "花小猪", 2, "10004",
                new Date(timeInMillis));
        // 编写SQL语句
        String sql = "insert into Animal " +
                "values(null,'"+animal.getName()+"',"+animal.getAge()+",'"+animal.getNum()+"','"+animal.getBirthday()+"');";

        // 使用try-with 自动关闭资源
        try (
                // 3.获取连接对象
                Connection connection = DriverManager.getConnection(url, user, password);
                // 4.获取发送对象
                Statement statement = connection.createStatement()) {
            // 5.执行SQL
            int result = statement.executeUpdate(sql);
            // 6.接收反馈信息
            System.out.println(result != 0 ? "插入成功" : "插入失败");
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }
}

四、删

package com.bdqn.animal;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

public class Delete {
    public static void main(String[] args) {
        // 1.加载驱动
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        }

        // 2.准备数据
        String url = "jdbc:mysql://127.0.0.1:3306/jdbcdatabase";
        String user = "root";
        String password = "123456";
        String sql = "delete from animal where name = '花小猪';";

        try (
                // 3.获取连接对象
                Connection connection = DriverManager.getConnection(url, user, password);
                // 4.获取发送对象
                Statement statement = connection.createStatement()) {
            // 5.执行SQL
            int result = statement.executeUpdate(sql);
            // 6.接收反馈信息
            System.out.println(result != 0 ? "删除成功" : "删除失败");
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }

    }
}

五、改

package com.bdqn.animal;

import java.sql.*;

public class Update {
    public static void main(String[] args) {
        // 1.加载驱动
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        }

        // 2.准备工作
        String url = "jdbc:mysql://127.0.0.1:3306/jdbcdatabase";
        String user = "root";
        String password = "123456";
        Animal animal = new Animal();
        animal.setBirthday(new Date(121,2,4));
        String sql = "update animal set `birthday` = '"+animal.getBirthday()+"' where name='花小猫'";

        try (
                // 3.获取连接对象
                Connection connection = DriverManager.getConnection(url, user, password);
                // 4.获取发送对象
                Statement statement = connection.createStatement()) {
            // 5.执行SQL
            int result = statement.executeUpdate(sql);
            // 6.接收反馈信息
            System.out.println(result != 0 ? "修改成功" : "修改失败");
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }
}

六、查

package com.bdqn.animal;

import java.sql.*;
import java.util.ArrayList;

public class SelectAll {
    public static void main(String[] args) {
        // 1.加载驱动
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        }

        // 2.准备数据
        String url = "jdbc:mysql://127.0.0.1:3306/jdbcdatabase";
        String user = "root";
        String password = "123456";
        String sql = "select * from animal";

        try(
                // 3.获取连接对象
                Connection connection = DriverManager.getConnection(url, user, password);
                // 4.获取发送对象
                Statement statement = connection.createStatement()
        ) {
            // 5.执行SQL
            ResultSet resultSet = statement.executeQuery(sql);
            // 6.获取集合中的一条记录
            // 创建ArrayList集合 存放Animal对象
            ArrayList animalArrayList = new ArrayList<>();
            while (resultSet.next()){
                // 按索引获取，从1开始     也可以使用使用字段名如getInt(aid)
                int aid = resultSet.getInt(1);
                String name = resultSet.getString(2);
                int age = resultSet.getInt(3);
                String num = resultSet.getString(4);
                Date birthday = resultSet.getDate(5);
                // 创建Animal对象
                Animal animal = new Animal(aid, name, age, num, birthday);
                animalArrayList.add(animal);
            }
            // 7.遍历ArrayList集合
            for(Animal a : animalArrayList)
                System.out.println(a);

        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }
}

 七、细节过程都在注释里