Javaweb-JDBC

JDBC

什么是JDBC

JDBC（Java DataBase Connectivity）是Java和数据库之间的一个桥梁，是一个规范而不是一个实现，能够执行sql语句。它由一组用Java语言编写的类和接口组成。各种不同类型的数据库都有相应的实现
IDEA连接数据库
1.添加maven依赖

<dependencies>
        <dependency>
        <groupId>MysqL</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.28</version>
    </dependency>

2.实现MysqL的连接

3.java代码实现

package com.wang;

import java.sql.*;

public class test {
    public static void main(String[] args) throws ClassNotFoundException, sqlException {
        //配置信息
        String url="jdbc:MysqL://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai&useSSL=false&allowPublicKeyRetrieval=true";
        String username="root";
        String password="wjs790929";
    //加载驱动
     Class.forName("com.MysqL.cj.jdbc.Driver");
      //连接数据库
        Connection connection = DriverManager.getConnection(url, username, password);
        //向数据库发送sql的对象Statement:增删改查
        Statement statement = connection.createStatement();
        //编写sql
String sql="select * from user";
//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"));
        }
        //关闭连接释放资源
        resultSet.close();
        statement.close();
        connection.close();

    }
}

4.增删改返回的是int型，用executeupdate
5.采用预编译经行sql操作更加完善更加安全

package com.wang;

import java.sql.*;

public class test02 {
    public static void main(String[] args) throws ClassNotFoundException, sqlException {
        //配置信息
        String url="jdbc:MysqL://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai&useSSL=false&allowPublicKeyRetrieval=true";
        String username="root";
        String password="wjs790929";
        //加载驱动
        Class.forName("com.MysqL.cj.jdbc.Driver");
        //连接数据库
        Connection connection = DriverManager.getConnection(url, username, password);
        //编写sql
        String sql="insert into jdbc.user(id, NAME, PASSWORD, email) VALUES (?,?,?,?)";
        //预编译
        PreparedStatement preparedStatement = connection.prepareStatement(sql);
        preparedStatement.setInt(1,4);
        preparedStatement.setString(2,"jinnice");
        preparedStatement.setString(3,"113456");
        preparedStatement.setString(4,"[e-mail]");
        //执行sql
        int i = preparedStatement.executeUpdate();
        if(i>=1)
        {
            System.out.println("成功");
        }
        //关闭连接释放资源
        preparedStatement.close();
        connection.close();

    }
}

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