如何使用PHP开发微信小程序的在线课程功能？

<?php
// 连接数据库
$servername = "localhost";
$username = "your_username";
$passWord = "your_password";
$dbname = "your_database";

$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
    die("数据库连接失败: " . $conn->connect_error);
}

// 获取课程列表
$sql = "SELECT * FROM courses";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    $courses = array();
    while($row = $result->fetch_assoc()) {
        $course = array(
            'id' => $row['id'],
            'name' => $row['name'],
            'description' => $row['description'],
            // 其他字段
        );
        array_push($courses, $course);
    }
    // 将课程列表以JSON格式返回
    echo json_encode($courses);
} else {
    echo "没有找到课程";
}
$conn->close();
?>

wx.request({
  url: 'https://your_domain.com/api/courses.php',
  success: function(res) {
    // 将后端返回的JSON数据转换为课程列表
    var courses = JSON.parse(res.data);
    // 处理课程列表，例如显示在页面上
    // ...
  }
})