技术分享 ——JDBC

技术分享 ——JDBC

导入依赖

在使用 JDBC 前，首先要导入数据库依赖，每个数据库依赖不同。例如，MYSQL 的依赖如下：

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.31</version>
</dependency>

将该段代码放在 pom 文件的<dependencies>下。

配置 MySQL

首先检查 MySQL 是否安装，安装后可在 IDEA 中链接数据库。新建 MySQL 的链接。

代码实现

增

import java.sql.*;

public class insert {
    public static void main(String[] args) throws Exception {
        String url="jdbc:mysql://localhost:3306/student";
        String user="root";
        String password="yourpassword";
        Connection connection=DriverManager.getConnection(url,user,password);

        PreparedStatement preparedStatement = connection.prepareStatement("insert into user(name,age) values(?,?)");
        preparedStatement.setString(1,"小美");
        preparedStatement.setInt(2,18);
        int i = preparedStatement.executeUpdate();
        if(i>0){
            System.out.println("插入成功");
        }else {
            System.out.println("插入失败");
        }
        connection.close();
    }
}

删

import java.sql.*;

public class delete {
    public static void main(String[] args) {
        String jdbcURL = "jdbc:mysql://localhost:3306/student";
        String username = "root";
        String password = "yourpassword";

        try (Connection connection = DriverManager.getConnection(jdbcURL, username, password);
             PreparedStatement preparedStatement = connection.prepareStatement("delete from user where name=? and id=?")) {
            preparedStatement.setString(1, "xiaohong");
            preparedStatement.setInt(2, 1);
            int rowsAffected = preparedStatement.executeUpdate();
            System.out.println("Rows affected: " + rowsAffected);

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

改

import java.sql.*;

public class update {
    public static void main(String[] args) {
        String jdbcURL = "jdbc:mysql://localhost:3306/student";
        String username = "root";
        String password = "yourpassword";

        try (Connection connection = DriverManager.getConnection(jdbcURL, username, password);
             PreparedStatement preparedStatement = connection.prepareStatement("update user set name = ? where id = ?")) {
            preparedStatement.setString(1, "xiaohong");
            preparedStatement.setInt(2, 1);
            int rowsAffected = preparedStatement.executeUpdate();
            System.out.println("Rows affected: " + rowsAffected);

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

查

import java.sql.*;

public class select {
    public static void main(String[] args) {
        String jdbcURL = "jdbc:mysql://3306/student";
        String username = "root";
        String password = "yourpassword";

        try (Connection connection = DriverManager.getConnection(jdbcURL, username, password);
             PreparedStatement preparedStatement = connection.prepareStatement("SELECT id,name FROM user")) {

            ResultSet resultSet = preparedStatement.executeQuery();

            while (resultSet.next()) {
                String name = resultSet.getString("name");
                int id = resultSet.getInt("id");

                System.out.println("Column1: " + id + ", Column2: " + name);
            }

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