基于自定义PDO数据库连接类的数据获取问题求助

Hey there! Let's fix up how you use your custom PDO class to fetch data from your database. First, let's address a couple of small issues in your existing dbconnect class, then walk through the correct way to run your query.

1. Fix the Custom PDO Class #

Since you're extending the native PDO class, you don't need a separate $dbh property—your dbconnect instance is a PDO connection. Also, we'll add proper error handling to make debugging easier:

class dbconnect extends PDO {
    private $dbengine = 'mysql';
    private $dbhost = 'localhost';
    private $dbuser = 'root';
    private $dbpassword = 'root';
    private $dbname = 'nesiojami';

    public function __construct() {
        try {
            // Call the parent PDO constructor to initialize the connection
            parent::__construct(
                "$this->dbengine:host=$this->dbhost;dbname=$this->dbname",
                $this->dbuser,
                $this->dbpassword
            );
            // Set default fetch mode (you had this right!)
            $this->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_OBJ);
            // Enable exception-based error handling (critical for debugging)
            $this->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        } catch (PDOException $e) {
            // Throw a meaningful error instead of silently failing
            throw new Exception("Database connection failed: " . $e->getMessage());
        }
    }
}

2. Use the Class to Fetch Data #

Now that the class is fixed, here's how to execute your query correctly. Important note: Your field names have hyphens (client-name, client-surname), so you need to wrap them in backticks ` to avoid MySQL parsing errors (it would otherwise interpret client-name as client - name):

// Create an instance of your custom connection class
$db = new dbconnect();

try {
    // Run the query (note the backticks around field names)
    $stmt = $db->query("SELECT `client-name`, `client-surname` FROM clients");
    // Fetch results as an associative array (overrides the default FETCH_OBJ)
    $clients = $stmt->fetchAll(PDO::FETCH_ASSOC);

    // Check out your data!
    print_r($clients);
} catch (PDOException $e) {
    echo "Query failed: " . $e->getMessage();
}

Key Takeaways #

• When extending PDO, your class inherits all PDO methods directly—no need to use a separate $dbh property.
• Always wrap field/table names with special characters (like hyphens) in backticks to avoid syntax errors.
• Enabling PDO::ERRMODE_EXCEPTION ensures you get clear error messages instead of silent failures, which makes debugging way easier.

内容的提问来源于stack exchange，提问作者ErikasR