PHP未定義函數

Question

我目前正在處理PHP和MySQL中的消息顯示。
我總是在第22行此錯誤：

Fatal error: Call to undefined function query() in ...

但我在這個特定行定義的$查詢....
我的代碼如下：

<?php 

$servername = "localhost"; 
$username = "root"; 
$password = ""; 
$dbname = "dbmitarbeiter"; 

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

$useremp = $_SESSION['username'];  

$query = " 
SELECT * 
FROM `tbabonnenten` s 
WHERE dest = " . $db->real_escape_string($useremp); 

$result = $db-query($query); 

if (!$result) { 
    echo 'SQL error ' . mysql_error(); 
    exit; 
} 

$user = $result->fetch_assoc(); 

/* 
* Run this query, and fetch the entire userrow, and put into $user 
* An alternative could be to just store the entire user array into 
* $_SESSION, as you wont have to query the database twice. 
*/ 

$tofetch = array(); 

for ($i=1; $i<=3; $i++) 
{ 
    //Let's check msg1, msg2, msg3 
    if ($user['abo' . $i]) 
    { 
     $tofetch[] = "name = 'Forum" . $i . "'"; 
    } 
} 

/* 
* If tbsubscribers has a '1' in msg1, and a '1' in msg2 then the array 
* will look like this: 
* array(
* 0 => "name = 'msg1'" 
* 1 => "name = 'msg2'" 
*) 
*/ 

//Throw an exception if all 'msg1', 'msg2', and 'msg3' are all 0 (Otherwise the query will fail) 
if (empty($tofetch)) { 
    echo "no subscriptions to show"; 
    //Don't continue here, otherwise the query will fail. 
    exit; 
} 

/* 
* Now it's a simple query. $tofetch will be imploded, to form a nice 
* where statement. Using the example above, it will look like: 
* name = 'msg1' OR name = 'msg2' 
*/ 

$query = " 
SELECT * 
FROM `tbmitteilung` 
WHERE " . implode(' OR ', $tofetch); 

$result = $db->query($query); 

if (!$result) { 
    echo 'SQL error ' . mysql_error(); 
    exit; 
} 

$messages = $result->fetch_all(MYSQLI_ASSOC); 

print_r($messages); 



?> 

任何想法？ 感謝您的幫助提前

Answer 1

錯別字：

$result = $db-query($query); 
      ^---- mathematical subtraction 

你想要的（例如， 「未定義功能查詢（）$ DB減去結果內容」）

$result = $db->query($query); 
      ^^----object member operator