需要jar包的支持：

java.sql javax.sql mysql-connection-java…(连接驱动) 导入jar包

 <dependencies>         <dependency>             <groupId>mysql</groupId>             <artifactId>mysql-connector-java</artifactId>             <version>5.1.47</version>         </dependency>     </dependencies> 

创建数据库

DROP TABLE `users`;   CREATE TABLE `users`(   `id` INT PRIMARY KEY,   `name` VARCHAR(50) NOT NULL,   `password` VARCHAR(40) NOT NULL,   `email` VARCHAR(60) NOT NULL,   `birthday` DATE ) ENGINE=INNODB DEFAULT CHARSET=utf8  INSERT INTO `users` (`id`, `name`, `password`, `email` `birthday`) VALUES('1','张三','123456','zs@sina.com','2021-07-14'); INSERT INTO `users` (`id`, `name`, `password`, `email`, `birthday`) VALUES('2','李四','123456','lisi@sina.com','1981-12-04'); INSERT INTO `users` (`id`, `name`, `password`, `email`, `birthday`) VALUES('3','王五','123456','wangwu@sina.com','1982-12-04'); INSERT INTO `users` (`id`, `name`, `password`, `email`, `birthday`) VALUES('4','赵六','123456','zhaoliu@sina.com','1987-12-05'); INSERT INTO `users` (`id`, `name`, `password`, `email`, `birthday`) VALUES('5','钱七','123456','qianqi@sina.com','2021-07-19'); INSERT INTO `users` (`id`, `name`, `password`, `email`, `birthday`) VALUES('6','刘八','123456','liuba@sina.com','2021-07-19'); 

idea连接数据库（6步曲）

package com.jdbc.test;

import java.sql.*;

public class TestJdbc { 
        
    public static void main(String[] args) throws ClassNotFoundException, SQLException { 
        
        String url = "jdbc:mysql://localhost:3306/jdbcstudy?useUnicode=true&characterEncoding=utf8&useSSL=false";
        String username = "root";
        String password = "123456";

        //加载驱动
        Class.forName("com.mysql.jdbc.Driver");
        //连接数据库
        Connection connection = DriverManager.getConnection(url, username, password);
        //创建Statement
        Statement statement = connection.createStatement();
        //编写sql
        String sql="select * from users";
        //执行sql
        ResultSet resultSet = statement.executeQuery(sql);
        while (resultSet.next()){ 
        
            System.out.println("id=:"+ resultSet.getObject("id"));
            System.out.println("NAME=:"+ resultSet.getObject("NAME"));
            System.out.println("PASSWORD=:"+ resultSet.getObject("PASSWORD"));
            System.out.println("email=:"+ resultSet.getObject("email"));
            System.out.println("birthday=:"+ resultSet.getObject("birthday"));

        }
        //关闭连接
        resultSet.close();
        statement.close();
        connection.close();
    }
}

预编译sql 防止mysql注入

public class Test2Jdbc { 
        
    public static void main(String[] args) { 
        
        String url = "jdbc:mysql://localhost:3306/jdbcstudy?useUnicode=true&characterEncoding=utf-8";
        String user = "root";
        String pwd = "123456";
        try { 
        

            //1. 加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            //2. 连接数据库
            Connection con = DriverManager.getConnection(url, user, pwd);

            //3.sql
            String str = "insert into users(id, name, password, email, birthday) values (?,?,?,?,?)";
            //4. 预编译
            PreparedStatement statement = con.prepareStatement(str);
            statement.setInt(1,8);
            statement.setString(2,"小红");
            statement.setString(3,"123456");
            statement.setString(4,"xiaohong@sina.com");
            statement.setDate(5,new java.sql.Date(System.currentTimeMillis()));


            //5.执行sql
            int count = statement.executeUpdate();

            if (count > 0) { 
        
                System.out.println("插入成功！");
            }
            statement.close();
            con.close();

        } catch (ClassNotFoundException e) { 
        
            e.printStackTrace();
        } catch (SQLException e) { 
        
            e.printStackTrace();
        }
    }
}

jdbc 事务

开启事务 事务提交 commit() 事务回滚 rollback() 关闭事务

转账： A:1000 B:1000

A(900) —100–> B(1100) 构建数据库

CREATE TABLE `account`(
  `id` INT PRIMARY KEY,
  `name` VARCHAR(50) NOT NULL,
  `money` FLOAT NOT NULL
) ENGINE=INNODB DEFAULT CHARSET=utf8

INSERT INTO `account` (`id`, `name`, `money`) VALUES(1,'A',1000);
INSERT INTO `account` (`id`, `name`, `money`) VALUES(2,'B',1000);
INSERT INTO `account` (`id`, `name`, `money`) VALUES(3,'C',1000);

idea

import org.junit.Test;

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

/** * @ClassName: Test3Jdbc * @Description: TODO 类描述 * @Author: zyy * @Date: 2021/12/16 21:11 * @Version: 1.0 */
public class Test3Jdbc { 
        

    @Test
    public void test() { 
        

        String url = "jdbc:mysql://localhost:3306/jdbcstudy?useUnicode=true&characterEncoding=utf-8";
        String user = "root";
        String pwd = "123456";
        Connection con = null;
        try { 
        

            Class.forName("com.mysql.jdbc.Driver");
            con = DriverManager.getConnection(url, user, pwd);


            //开启事务 这里不开启事务的话异常情况就会有问题 false是开启
            con.setAutoCommit(false);

            con.prepareStatement("update account set money=money-100 where name='A'").executeUpdate();

            //制造错误
// int i = 1 / 0;

            con.prepareStatement("update account set money=money+100 where name='B'").executeUpdate();

            con.commit();

            System.out.println("success");

        } catch (Exception e) { 
        
            System.out.println("error rollback");
            if (con != null) { 
        
                try { 
        
                    con.rollback();
                } catch (SQLException ex) { 
        
                    ex.printStackTrace();
                }
            }


        } finally { 
        
            if (con != null) { 
        
                try { 
        
                    con.close();
                } catch (SQLException e) { 
        
                    e.printStackTrace();
                }
            }
        }

    }
}

项目讲解