1)什么是JDBC

java database connect(java连接数据库)

需要jar包的支持：

• Java.sql
• javax.sql
• mysql-connector-java

2)数据库建表

关键词重复用符号飘`围起来:

3)idea连接mysql

pom.xml导入依赖

    <dependencies>
        <!--mysql的驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.11</version>
        </dependency>
    </dependencies>

连接成功：

4)jdbc固定步骤

Statement不安全的方式：

package com.kakafa.test;

import java.sql.*;

public class TestJDBC {
    public static void main(String[] args) throws ClassNotFoundException, SQLException {
        //配置信息
        //useUnicode=true&characterEncoding=utf-8解决中文乱码问题
        String url="jdbc:mysql://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT";
        String username="root";
        String password="123456";

        //加载驱动
        Class.forName("com.mysql.cj.jdbc.Driver");

        //连接数据库,代表数据库
        Connection connection = DriverManager.getConnection(url, username, password);

        //向数据库发送SQL的对象Statement:CRUD增删改查
        Statement statement = connection.createStatement();

        //编写sql
        String sql="select * from users";

        //执行sql,返回一个结果集
        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"));
        }
        //关闭连接释放资源
        resultSet.close();
        statement.close();
        connection.close();
    }
}

PreparedStatement安全的方式：

package com.kakafa.test;

import java.sql.*;

public class TestJDBC02 {
    public static void main(String[] args) throws ClassNotFoundException, SQLException {

        String url="jdbc:mysql://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT";
        String username="root";
        String password="123456";

        //加载驱动
        Class.forName("com.mysql.cj.jdbc.Driver");
        //连接数据库,代表数据库
        Connection connection = DriverManager.getConnection(url, username, password);


        //编写sql
        String sql="insert into users(id,name,password,email,birthday)values(?,?,?,?,?)";

        //预编译
        PreparedStatement preparedStatement = connection.prepareStatement(sql);

        preparedStatement.setInt(1,3);//给第一个占位符？赋值为1
        preparedStatement.setString(2,"李四");
        preparedStatement.setString(3,"333333");
        preparedStatement.setString(4,"14@qq.com");
        preparedStatement.setString(5,"2020-04-05");


        //执行sql
        int i=preparedStatement.executeUpdate();
        if (i>0){
            System.out.println("插入成功");
        }

        //关闭连接释放资源

        preparedStatement.close();
        connection.close();

    }
}

5）事务

要么都成功，要么都失败

ACID原则：保证数据的安全

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

package com.kakafa.test;

import java.sql.*;

public class TestJDBC02 {
    public static void main(String[] args) throws ClassNotFoundException, SQLException {

        String url="jdbc:mysql://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT";
        String username="root";
        String password="123456";

        //加载驱动
        Class.forName("com.mysql.cj.jdbc.Driver");
        //连接数据库,代表数据库
        Connection connection = DriverManager.getConnection(url, username, password);


        //编写sql
        String sql="insert into users(id,name,password,email,birthday)values(?,?,?,?,?)";

        //预编译
        PreparedStatement preparedStatement = connection.prepareStatement(sql);

        preparedStatement.setInt(1,3);//给第一个占位符？赋值为1
        preparedStatement.setString(2,"李四");
        preparedStatement.setString(3,"333333");
        preparedStatement.setString(4,"14@qq.com");
        preparedStatement.setString(5,"2020-04-05");


        //执行sql
        int i=preparedStatement.executeUpdate();
        if (i>0){
            System.out.println("插入成功");
        }

        //关闭连接释放资源

        preparedStatement.close();
        connection.close();

    }
}