PDO查詢類

Question

我正在修補一個'應該'允許我輕鬆執行fetchall查詢並在foreach語句中顯示結果的類。我假設所有工作正常，因爲我沒有錯誤。至於foreach - 這一定是問題嗎？我如何通過$connect->query()獲得結果？我是新來的，在我的函數中使用任何數據庫OOP框架，所以我可能完全錯誤的行。

<? 

error_reporting(1); 

class dbconnect { 

private $host; 
private $database; 
private $username; 
private $password; 

private $pdo; 
private $error; 

    public function __construct() { 

     $this->host  = "localhost";    // Host 
     $this->database = "images";     // Database Name 
     $this->username = "*";    // Username 
     $this->password = "*"; // Password 
     $options = array(
      PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8' 
     ); 

     try { 
      $this->pdo = new PDO("mysql:host={$this->host};dbname={$this->dbname};charset=utf8", $this->username, $this->password, $options); 
     } 
     catch(PDOException $e) { 
      $this->error = $e->getMessage(); 
     } 

    } 

    public function query($query) { 

     try { 
      $stmt = $this->pdo->prepare($query); 
      $stmt->execute(); 
     } catch(PDOException $ex) { 
      die("Failed to run query: " . $ex->getMessage()); 
     } 

     $rows = $stmt->fetchAll(); 
     return $rows; 

    } 

} 

$connect = new dbconnect; 
$rows = $connect->query("select * from photos"); 
foreach($rows as $row): 
    print $row['id']; 
endforeach; 



?> 

Answer 1

您在query內部聲明的$rows變量不能被外部訪問，它是該函數的本地變量。最有可能的，你只是想return這些結果給調用者：

$rows = $stmt->fetchAll(); 
return $rows; // return value from function... 

，並有來電捕捉在其自己的變量返回值：

$rows = $connect->query("select * from images"); // ... is received by caller 
foreach($rows as $row): 

還檢查了dougjore的答案，你在query方法內混合$this->stmt和$stmt。

Answer 2

很確定你是不是曾經實際執行查詢：

 $this->stmt = $this->pdo->prepare($query); 
     $stmt->execute(); 

我相信（我可能是錯的，我是相當新的PDO自己，我還沒有建立一個類爲此），你需要說$ this-> stmt-> execute（）;

Answer 3

你可以做

// PDO :: FETCH_ASSOC：返回按列名索引作爲你的結果返回數組設置

$this->stmt = $this->pdo->prepare($query); 
$this->stmt->execute(); 

while ($result = $this->stmt->fetch(PDO::FETCH_ASSOC)) 
{ 

    //do something with the result 
} 

看看這裏爲更多的選擇來獲取PDO查詢結果： http://php.net/manual/en/pdostatement.fetch.php

Answer 4

$connect = new dbconnect; 
$sql="select * from photos"; 
$stmt=$connect->pdo->prepare($sql); 
$stmt->execute(); 
$result=$stmt->fetch(PDO::FETCH_ASSOC); 
foreach($result as $key => $value) { 
    echo $key . "-" . $value . "<br/>"; 
}