PHP를 이용하여 개발된 쇼핑몰 상품평 기능에 대한 자세한 설명

CREATE TABLE comments (
  id INT AUTO_INCREMENT PRIMARY KEY,
  product_id INT NOT NULL,
  user_id INT NOT NULL,
  content TEXT NOT NULL,
  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
  updated_at DATETIME DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);

<?php
// 获取商品id
$product_id = $_GET['product_id'];

// 查询商品信息
// TODO

// 查询商品评论
$sql = "SELECT * FROM comments WHERE product_id = $product_id";
$result = mysqli_query($conn, $sql);

// 显示商品信息
// TODO

// 显示商品评论
while ($row = mysqli_fetch_assoc($result)) {
    echo "<div class='comment'>";
    echo "<p>{$row['content']}</p>";
    echo "<span class='timestamp'>{$row['created_at']}</span>";
    echo "</div>";
}
?>

<!-- 提交评论表单 -->
<form method="post" action="submit_comment.php">
    <input type="hidden" name="product_id" value="<?php echo $product_id ?>">
    <textarea name="content" placeholder="请输入评论内容"></textarea>
    <button type="submit">提交评论</button>
</form>

<?php
// 获取提交的评论信息
$product_id = $_POST['product_id'];
$user_id = $_SESSION['user_id'];
$content = $_POST['content'];

// 插入评论到数据库
$sql = "INSERT INTO comments (product_id, user_id, content) VALUES ($product_id, $user_id, '$content')";
$result = mysqli_query($conn, $sql);

// 判断评论是否插入成功
if ($result) {
    echo "评论提交成功！";
} else {
    echo "评论提交失败！";
}
?>

// 设置每页显示的评论数量
$commentPerPage = 10;

// 获取当前页码，默认为第一页
$page = isset($_GET['page']) ? $_GET['page'] : 1;

// 查询评论总数
$sql = "SELECT COUNT(*) AS total FROM comments WHERE product_id = $product_id";
$result = mysqli_query($conn, $sql);
$row = mysqli_fetch_assoc($result);
$totalComments = $row['total'];

// 计算总页数
$totalPages = ceil($totalComments / $commentPerPage);

// 查询当前页的评论
$offset = ($page - 1) * $commentPerPage;
$sql = "SELECT * FROM comments WHERE product_id = $product_id LIMIT $offset, $commentPerPage";
$result = mysqli_query($conn, $sql);

// 显示评论
while ($row = mysqli_fetch_assoc($result)) {
    // TODO
}

// 显示分页链接
for ($i = 1; $i <= $totalPages; $i++) {
    echo "<a href='product_detail.php?product_id=$product_id&page=$i'>$i</a> ";
}