如何在不刷新页面的情况下在php中统计视频点击量

<video id="video" src="video.mp4"></video>

<script>
  var video = document.getElementById('video');
  video.addEventListener('click', function() {
    // 使用AJAX发送请求
    var xhr = new XMLHttpRequest();
    xhr.open('POST', 'update_click_count.php', true);
    xhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
    xhr.onreadystatechange = function() {
      if (xhr.readyState === 4 && xhr.status === 200) {
        console.log(xhr.responseText);
      }
    };
    xhr.send('video_id=123'); // 传递视频的唯一标识符
  });
</script>

<?php
// 连接数据库
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";
$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
  die("连接失败: " . $conn->connect_error);
}

// 获取视频的唯一标识符
$video_id = $_POST['video_id'];

// 查询数据库中是否存在该视频的点击信息
$sql = "SELECT click_count FROM video_clicks WHERE video_id = '$video_id'";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
  // 如果存在，将点击量加1
  $row = $result->fetch_assoc();
  $click_count = $row['click_count'] + 1;
  $sql = "UPDATE video_clicks SET click_count = $click_count WHERE video_id = '$video_id'";
  $conn->query($sql);
} else {
  // 如果不存在，插入一条新的记录
  $sql = "INSERT INTO video_clicks (video_id, click_count) VALUES ('$video_id', 1)";
  $conn->query($sql);
}

$conn->close();

echo "点击量更新成功！";
?>