PDO查詢返回空

Question

我有一個連接類文件，它允許我的其他類「函數」連接到我的MySQL數據庫。但是，當我執行MySQL查詢時，它僅返回Array()。我選擇的數據其實就在那裏（我查過）。問題是什麼？

Connection.php

<?php 

class Connection extends PDO { 

private $username; 
private $password; 
private $database; 
private $hostname; 

public function __construct($hostname, $username, $password, $database) { 

    $this->hostname = $hostname; 
    $this->username = $username; 
    $this->password = $password; 
    $this->hostname = $hostname; 

    try { 
     parent::__construct("mysql:host=" . $this->hostname . ";dbname=" . $this->database, $this->username, $this->password); 
    } 

    catch (PDOException $e) { 
     echo $e->getMessage(); 
    } 
    } 
} 

?> 

的functions.php

<?php 

require_once "Connection.php"; 

class Functions { 

private $connection; 

public function __construct() { 
    $this->connection = new Connection("127.0.0.1", "xxx", "xxx", "xxx"); 
} 

public function sqlFetchAssoc($query) { 

    $sth = $this->connection->prepare($query); 
    $sth->execute(); 
    $result = $sth->fetchAll(PDO::FETCH_ASSOC); 

    return $result; 
    } 
} 

$functions = new Functions(); 
$row = $functions->sqlFetchAssoc("SELECT * FROM chatlogs WHERE id = 70"); 

print_r($row); 

?> 

Answer 1

我發現你在Connection.php錯誤：

$this->hostname = $hostname; 
$this->username = $username; 
$this->password = $password; 
$this->hostname = $hostname; 

$this->hostname重複而$this->database未設置。但是，您可以完全剝離設置$this->something，因爲您在相同的功能中使用這些值。這將使它更簡單：

try { 
    parent::__construct("mysql:host=" . $hostname . ";dbname=" . $database, $username, $password); 
} 

我建議更進一步。你應該分別測試測試。您可以在testfunction.php寫這個劇本並調試它（如果需要）：

<?php 
class Functions { 
private $connection; 

public function __construct() { 
    $this->connection = new PDO("mysql:host=127.0.0.1;dbname=xxx", "xxx", "xxx"); 
} 

public function sqlFetchAssoc($query) { 

    $sth = $this->connection->prepare($query); 
    $sth->execute(); 
    $result = $sth->fetchAll(PDO::FETCH_ASSOC); 

    return $result; 
    } 
} 

echo "Test started <br><br>"; 
echo "Initialization: <br>"; 
$functions = new Functions(); 
echo "Correct<br><br>"; 
echo "Performing a select: <br>"; 
$row = $functions->sqlFetchAssoc("SELECT * FROM chatlogs WHERE id = 70"); 
print_r($row); 
echo "Test finished."; 
?> 

然後做一流的類似的東西。那麼不僅可以更容易地發現錯誤，而且如果發生錯誤，您可以參加這些測試，看看出了什麼問題，而不是再次寫出錯誤。切記不要將它們包含在生產代碼中。