MySQLi পরিচিতি ও সংযোগ

MySQLi কী?

MySQLi (MySQL Improved) হলো PHP-র extension যা MySQL database-এর সাথে যোগাযোগ করে। পুরনো mysql_* function-এর আধুনিক সংস্করণ।

MySQLi vs PDO

	MySQLi	PDO
Database	শুধু MySQL	১২টি DB
API	OOP + Procedural	শুধু OOP
Named Params	❌	✅

Connection (OOP) ⭐

<?php
$conn = new mysqli("localhost", "root", "", "shop_db");

if ($conn->connect_error) {
    die("সংযোগ ব্যর্থ: " . $conn->connect_error);
}

$conn->set_charset("utf8mb4");    // বাংলা সমর্থন
echo "সফল";
$conn->close();
?>

Procedural

$conn = mysqli_connect("localhost", "root", "", "shop_db");
if (!$conn) die(mysqli_connect_error());
mysqli_set_charset($conn, "utf8mb4");

Reusable Class

<?php
class DB {
    private static $instance = null;
    private $conn;

    private function __construct() {
        $this->conn = new mysqli("localhost", "root", "", "shop_db");
        if ($this->conn->connect_error) {
            throw new Exception($this->conn->connect_error);
        }
        $this->conn->set_charset("utf8mb4");
    }

    public static function getInstance(): self {
        if (self::$instance === null) self::$instance = new self();
        return self::$instance;
    }

    public function getConnection(): mysqli {
        return $this->conn;
    }
}

$conn = DB::getInstance()->getConnection();
?>

Error Handling

try {
    $conn = new mysqli("localhost", "root", "", "shop_db");
    if ($conn->connect_error) throw new Exception($conn->connect_error);
    $conn->set_charset("utf8mb4");
} catch (Exception $e) {
    error_log("DB: " . $e->getMessage());
    http_response_code(500);
    die(json_encode(["error" => "DB সমস্যা"]));
}

Useful Properties

$conn->server_info     // MySQL version
$conn->affected_rows    // শেষ query এ প্রভাবিত
$conn->insert_id        // শেষ AUTO_INCREMENT id
$conn->error            // error message
$conn->errno            // error code