通知取消定義偏移PHP

Question

我想如果管理員更改頁面不可見，通過改變可見值爲零重定向頁面，什麼是錯我的代碼，我不斷收到錯誤

<?php 
$result = mysqli_query($con,"SELECT VISIBLE FROM menu WHERE id=0"); 
if($row = mysqli_fetch_array($result)) 
    { 
header('Location: ./unavailable.php? error=pagenotavaialbe'); 
} 
    else 
?> 

Answer 1

嘗試是這樣的

$result = mysqli_query($con,"SELECT VISIBLE FROM menu WHERE id=0"); 
if(mysqli_num_rows($result) == 0){ 
header('Location: ./unavailable.php? error=pagenotavaialbe'); 
exit; 
} else { 
$row = mysqli_fetch_array($result); 
//do your code here 
} 

Answer 2

試試這個：

if($result) 
{ 
    if($row = mysqli_fetch_array($result)) 
    { 
     header('Location: ./unavailable.php? error=pagenotavaialbe'); 
    } 
}