如何使用PHP开发员工考勤数据的权限管理功能？

<?php
// 获取用户输入的用户名和密码
$username = $_POST['username'];
$password = $_POST['password'];

// 根据用户名查询用户信息
$query = "SELECT * FROM users WHERE username = '$username'";
$result = mysqli_query($conn, $query);

// 验证用户输入的密码是否正确
if ($result && mysqli_num_rows($result) > 0) {
    $user = mysqli_fetch_assoc($result);
    if ($password == $user['password']) {
        // 登录成功，可进行相应操作
        // 将用户ID存入session供后续使用
        $_SESSION['user_id'] = $user['user_id'];
    } else {
        echo "密码错误";
    }
} else {
    echo "用户名不存在";
}

<?php
// 验证当前用户是否为管理员，如果不是则跳转到其他页面
if ($_SESSION['user_id'] != $admin_user_id) {
    header('Location: index.php');
    exit();
}

// 获取员工列表
$query = "SELECT * FROM users";
$result = mysqli_query($conn, $query);

// 显示员工列表以及设置权限
while ($user = mysqli_fetch_assoc($result)) {
    echo $user['username'];
    echo "<input type='checkbox' name='view_permission[]' value='".$user['user_id']."'/>查看权限";
    echo "<input type='checkbox' name='edit_permission[]' value='".$user['user_id']."'/>编辑权限";
    echo "<input type='checkbox' name='delete_permission[]' value='".$user['user_id']."'/>删除权限";
}

<?php
// 获取管理员设置的权限信息
$view_permission = $_POST['view_permission'];
$edit_permission = $_POST['edit_permission'];
$delete_permission = $_POST['delete_permission'];

// 更新权限信息
foreach ($view_permission as $user_id) {
    $query = "INSERT INTO permissions (user_id, view) VALUES ('$user_id', 1) ON DUPLICATE KEY UPDATE view=1";
    mysqli_query($conn, $query);
}

foreach ($edit_permission as $user_id) {
    $query = "INSERT INTO permissions (user_id, edit) VALUES ('$user_id', 1) ON DUPLICATE KEY UPDATE edit=1";
    mysqli_query($conn, $query);
}

foreach ($delete_permission as $user_id) {
    $query = "INSERT INTO permissions (user_id, delete) VALUES ('$user_id', 1) ON DUPLICATE KEY UPDATE delete=1";
    mysqli_query($conn, $query);
}