java数据库增删改查

Java中使用数据库进行增删改查需要借助JDBC（Java Database Connectivity）技术，具体步骤如下：

1. 加载数据库驱动

Class.forName("com.mysql.jdbc.Driver");

2. 建立数据库连接

Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC", "root", "password");

3. 创建Statement对象

Statement stmt = conn.createStatement();

4. 执行SQL语句

- 增加数据

String sql = "INSERT INTO users (name, age) VALUES ('Tom', 20)";
stmt.executeUpdate(sql);

- 删除数据

String sql = "DELETE FROM users WHERE id = 1";
stmt.executeUpdate(sql);

- 修改数据

String sql = "UPDATE users SET age = 21 WHERE id = 2";
stmt.executeUpdate(sql);

- 查询数据

String sql = "SELECT * FROM users";
ResultSet rs = stmt.executeQuery(sql);
while (rs.next()) {
    int id = rs.getInt("id");
    String name = rs.getString("name");
    int age = rs.getInt("age");
    System.out.println("id: " + id + ", name: " + name + ", age: " + age);
}

5. 关闭数据库连接

rs.close();
stmt.close();
conn.close();

完整的Java数据库增删改查示例代码如下：

import java.sql.*;

public class Main {
    public static void main(String[] args) throws ClassNotFoundException, SQLException {
        // 加载数据库驱动
        Class.forName("com.mysql.jdbc.Driver");

        // 建立数据库连接
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC", "root", "password");

        // 创建Statement对象
        Statement stmt = conn.createStatement();

        // 增加数据
        String sql = "INSERT INTO users (name, age) VALUES ('Tom', 20)";
        stmt.executeUpdate(sql);

        // 删除数据
        sql = "DELETE FROM users WHERE id = 1";
        stmt.executeUpdate(sql);

        // 修改数据
        sql = "UPDATE users SET age = 21 WHERE id = 2";
        stmt.executeUpdate(sql);

        // 查询数据
        sql = "SELECT * FROM users";
        ResultSet rs = stmt.executeQuery(sql);
        while (rs.next()) {
            int id = rs.getInt("id");
            String name = rs.getString("name");
            int age = rs.getInt("age");
            System.out.println("id: " + id + ", name: " + name + ", age: " + age);
        }

        // 关闭数据库连接
        rs.close();
        stmt.close();
        conn.close();
    }
}