所以我这里的php是一个更新的mysql查询，声明如果令牌<10，则返回“some error”。。问题是每次执行代码时它都返回错误。以同样的方式每次即使令牌=11。。我根本不懂完整的代码
//如果未登录，请重定向到登录页

if(!$user->is_logged_in()){ header('Location: login.php'); exit(); }

//定义页面标题

$title = 'Dashboard ~ Pixel Jag.';

//包含页眉模板

require('layout/header.php'); 
?>
<div class="container">
<div class="panel panel-default">
 <?php
$servername = "localhost";
$username = "user";
$password = "pass";
$dbname = "database";

//创建连接

$db = mysqli_connect($servername, $username, $password, $dbname);

//检查连接

if (!$db) {
die("Connection failed: " . mysqli_connect_error());
}
if (($_SESSION['tokens'] < 10)) {
echo "<ul class='list-group'><li class='list-group-item list-group-item-danger'>You do not have enough tokens!</li></ul>";
}
else {
$sql = "UPDATE members SET tokens=tokens - 10, tokenstatus='(Pending Tokens)' ,tokenswith=tokenswith + 10, tokenstatus1='(Pending Tokens)' WHERE username = '".($_SESSION['username']) ."'";
}
if (mysqli_query($db, $sql)) {
echo "<ul class='list-group'><li class='list-group-item list-group-item-success'><h4>Record updated successfully!</h4></li></ul>";
} else {
echo "Error updating record: " . mysqli_error($db);
}

mysqli_close($db);
?> 

<div class="panel-footer">
<a href="index.php"><h4>Back To Dashboard..</h4></a>
</div>
</div>
</div>
<?php

//包含页眉模板

require('layout/footer.php'); 
?>