اتصال به دیتابیس MySQL در برنامه‌های PHP

DB_HOST=annapurna.liara.cloud
DB_PORT=34663
DB_DATABASE=dreamy_zhukovsky
DB_USERNAME=root
DB_PASSWORD=Umtdo7rWEoEMyWth4nS1sf4t

<?php
$servername = getenv('DB_HOST');
$port = getenv('DB_PORT'); 
$username = getenv('DB_USERNAME'); 
$password = getenv('DB_PASSWORD'); 
$database = getenv('DB_DATABASE'); 

$conn = new mysqli($servername, $username, $password, $database, $port);

if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} else {
    echo "Connected";}

$conn->close();
?> 

<?php

$servername = getenv('DB_HOST');
$port = getenv('DB_PORT'); 
$database = getenv('DB_DATABASE'); 

$dsn = "mysql:host=$servername; port=$port; dbname=$database";
$username = getenv('DB_USERNAME');
$password = getenv('DB_PASSWORD'); 

try {
    
    $pdo = new PDO($dsn, $username, $password, [
        PDO::ATTR_PERSISTENT => true
    ]);

    echo "connection successfull.";
} catch (PDOException $e) {
    echo 'connection failed: ' . $e->getMessage();
}