PHP开发商城中的商品评分统计功能实现方法

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

// 查询商品信息
$query = "SELECT * FROM product WHERE id = $product_id";
$result = mysqli_query($conn, $query);
$product = mysqli_fetch_array($result);

// 查询评分统计信息
$query = "SELECT AVG(rating) AS average_rating, COUNT(*) AS total_ratings FROM rating WHERE product_id = $product_id";
$result = mysqli_query($conn, $query);
$rating_info = mysqli_fetch_array($result);

// 输出评分统计信息
echo "商品名称：" . $product['name'] . "<br>";
echo "商品价格：" . $product['price'] . "<br>";
echo "平均评分：" . $rating_info['average_rating'] . "<br>";
echo "总评分数：" . $rating_info['total_ratings'] . "<br>";
?>

<?php
// 处理用户提交的评分表单
if(isset($_POST['rating'])) {
  // 获取用户ID
  $user_id = $_SESSION['user_id'];
  
  // 获取商品ID
  $product_id = $_GET['product_id'];
  
  // 获取评分
  $rating = $_POST['rating'];
  
  // 插入评分记录
  $query = "INSERT INTO rating (product_id, user_id, rating) VALUES ($product_id, $user_id, $rating)";
  mysqli_query($conn, $query);
  
  // 刷新当前页面
  header("Location: product.php?product_id=$product_id");
  exit();
}

// 输出评分表单
echo "<form action='product.php?product_id={$product['id']}' method='post'>";
echo "评分：<input type='number' name='rating' min='1' max='5' required>";
echo "<input type='submit' value='提交'>";
echo "</form>";
?>

// 更新评分统计信息
$query = "UPDATE product SET average_rating = (SELECT AVG(rating) FROM rating WHERE product_id = $product_id), total_ratings = (SELECT COUNT(*) FROM rating WHERE product_id = $product_id) WHERE id = $product_id";
mysqli_query($conn, $query);