通过SQL查询更新列

Question

我已经制作了一个PHP脚本来升级他/她的防火墙应用程序（我的网站的一个功能）。我写了这样的代码：

<?php 
session_start(); 
include_once 'dbconnect.php'; 
$servername = "localhost"; 
$username = "root"; 
$password = ""; 
$dbname = "dbtest"; 

// Create connection 
$conn = new mysqli($servername, $username, $password, $dbname); 
// Check connection 
if ($conn->connect_error) { 
die("Connection failed: " . $conn->connect_error); 
} 

if(!isset($_SESSION['user'])) 
{ 
header("Location: index.php"); 
} 
$query = "UPDATE users SET firewall = firewall + 1, money = money - 300 WHERE user_id=".$_SESSION['user']")"; 
?> 

请帮我看看我做错了什么。

Answer 1

$query = "UPDATE users SET firewall = firewall + 1, money = money - 300 WHERE user_id=".$_SESSION['user']; 
$update = mysqli_query($conn,$query);