Check out example codes for "pdo connexion". It will help you in understanding the concepts better.

Code Example 1

public static function connexionBDD()
    {
        $base = null;

        try {
            $base = new PDO('mysql:host=' . MYSQL_HOSTNAME . '; dbname=' . MYSQL_DATABASE . '', MYSQL_USERNAME, MYSQL_PASSWORD);
        } catch (exception $e) {
            die('Erreur ' . $e->getMessage());
        }

        return $base;
    }

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