jdbc的增删改查代码

以下是Java JDBC实现数据库的增删改查代码示例：

1. 导入相关的包

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

2. 建立数据库连接

String url = "jdbc:mysql://localhost:3306/test";
String user = "root";
String password = "123456";
Connection conn = null;
try {
    //加载驱动
    Class.forName("com.mysql.jdbc.Driver");
    //获取连接
    conn = DriverManager.getConnection(url, user, password);
} catch (ClassNotFoundException | SQLException e) {
    e.printStackTrace();
}

3. 插入数据

String sql = "INSERT INTO user(name, age) VALUES(?, ?)";
try (PreparedStatement ps = conn.prepareStatement(sql)) {
    ps.setString(1, "Tom");
    ps.setInt(2, 20);
    int count = ps.executeUpdate();
    if (count > 0) {
        System.out.println("添加成功！");
    } else {
        System.out.println("添加失败！");
    }
} catch (SQLException e) {
    e.printStackTrace();
}

4. 更新数据

String sql = "UPDATE user SET age=? WHERE name=?";
try (PreparedStatement ps = conn.prepareStatement(sql)) {
    ps.setInt(1, 22);
    ps.setString(2, "Tom");
    int count = ps.executeUpdate();
    if (count > 0) {
        System.out.println("更新成功！");
    } else {
        System.out.println("更新失败！");
    }
} catch (SQLException e) {
    e.printStackTrace();
}

5. 删除数据

String sql = "DELETE FROM user WHERE name=?";
try (PreparedStatement ps = conn.prepareStatement(sql)) {
    ps.setString(1, "Tom");
    int count = ps.executeUpdate();
    if (count > 0) {
        System.out.println("删除成功！");
    } else {
        System.out.println("删除失败！");
    }
} catch (SQLException e) {
    e.printStackTrace();
}

6. 查询数据

String sql = "SELECT * FROM user";
try (PreparedStatement ps = conn.prepareStatement(sql)) {
    ResultSet rs = ps.executeQuery();
    while (rs.next()) {
        String name = rs.getString("name");
        int age = rs.getInt("age");
        System.out.println(name + " " + age);
    }
} catch (SQLException e) {
    e.printStackTrace();
}

7. 关闭数据库连接

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