如何實現在類中使用mysqli的函數？

Question

我已經創建了包含函數的類，並且該函數使用了mysqli。但是當我打電話給它時，它不起作用。

這裏是我的代碼

連接

dbconfig.php

define('DB_SERVER', 'localhost'); 
define('DB_USERNAME', 'root'); 
define('DB_PASSWORD', 'xxxx'); 
define('DB_DATABASE', 'sample_db'); 
define('PORT', '80'); 
define('SOCKET', '/var/lib/mysql/mysql.sock'); 
$connection = mysqli_connect(DB_SERVER, DB_USERNAME, DB_PASSWORD, DB_DATABASE, PORT, SOCKET) or die("Error " . mysqli_error($connection)); 
mysqli_set_charset($connection, "utf8"); 

類用戶

class.php

include('dbconfig.php'); 
class User{ 
    function checkUser($ID, $U_Name){ 
    $query = mysqli_query($connection, "SELECT * FROM user WHERE ID = '$ID'") 
      or die(mysqli_error($connection)); 
    $result = mysqli_fetch_array($query, MYSQLI_ASSOC); 

    if (!empty($result)) { 
     # User is already present 
     $query = mysqli_query($connection, "UPDATE user SET U_Name = '$U_Name' 
       WHERE ID = '$ID'") or die(mysqli_error($connection)); 
     $query = mysqli_query($connection, "SELECT * FROM user WHERE ID = '$ID'"); 
     $result = mysqli_fetch_array($query, MYSQLI_ASSOC); 
     return $result; 
    } 
    else{ 
     #user not present. Insert a new Record 
    } 

    return $result; 
    } 
} 

調用代碼

include('dbconfig.php'); 
include('class.php'); 
$uid = $user_info->id; //1280 
$user_name = $user_info->name; //Mr. AAAA 

$user = new User(); 
if($uid != "" && $uid != null){ 
    $userdata = $user->checkUser($uid, $user_name); 
    if(!empty($userdata)){ 
    //do something 
    } 
} 

你能幫我解決這個問題？

預先感謝！

Answer 1

這將解決它：通過global使該範圍內的變量可訪問。

class User{ 
    function checkUser($ID, $U_Name){ 
    global $connection; 
    // ... 
    } 
} 

在這裏閱讀更多：在每一個功能http://php.net/manual/en/language.variables.scope.php

Answer 2

重新聲明連接變量使用像或者

 function checkUser($ID, $U_Name){ 
      global $connection; 
       $query = mysqli_query($connection, "SELECT * FROM user WHERE ID = '$ID'") 
      or die(mysqli_error($connection)); 
    $result = mysqli_fetch_array($query, MYSQLI_ASSOC); 

    if (!empty($result)) { 
     # User is already present 
     $query = mysqli_query($connection, "UPDATE user SET U_Name = '$U_Name' 
       WHERE ID = '$ID'") or die(mysqli_error($connection)); 
     $query = mysqli_query($connection, "SELECT * FROM user WHERE ID = '$ID'"); 
     $result = mysqli_fetch_array($query, MYSQLI_ASSOC); 
     return $result; 
    } 
    else{ 
     #user not present. Insert a new Record 
    } 

    return $result; 
      }