php 仿盖楼式评论

<?php
// 数据库连接
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "comment_db";

$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 获取评论
$sql = "SELECT * FROM comments ORDER BY id DESC";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        echo "<div class='comment'>";
        echo "<p>" . $row["content"] . "</p>";
        echo "<p>By " . $row["username"] . " on " . $row["date"] . "</p>";
        if ($row["parent_id"] == 0) {
            getReplies($row["id"]);
        }
        echo "</div>";
    }
} else {
    echo "没有评论";
}

$conn->close();

function getReplies($parent_id) {
    global $conn;
    $sql = "SELECT * FROM comments WHERE parent_id = $parent_id ORDER BY id ASC";
    $result = $conn->query($sql);

    if ($result->num_rows > 0) {
        while($row = $result->fetch_assoc()) {
            echo "<div class='reply'>";
            echo "<p>" . $row["content"] . "</p>";
            echo "<p>By "": " . $row["username"] . " on " . $row["date"] . "</p>";
            getReplies($row["id"]);
            echo "</div>";
        }
    }
}
?>