รบกวนขอคำแนะนำ การเขียน class php ติดต่อ MySQL ด้วยคับ

<?php
	// Database host name
	define('DB_HOST', 'localhost');

	// Database user name
	define('DB_USER', 'root');

	// Database name
	define('DB_NAME', 'demo');

	// Database password
	define('DB_PASS', '1234');
	
	// Data source name..
	$dsn = "mysql:host=" . DB_HOST . ";dbname=" . DB_NAME;

	// Default charset.
	$charset = array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8");
	
	try {
		// Connect to postgres object databse.
		$dbo = new PDO($dsn, DB_USER, DB_PASS, $charset);
	} catch(PDOException $e) {
		// If can't connect display error message
		throw new PDOException(
			'<pre><h1>Connection failed:</h1> ' . $e->getMessage() . '</pre>'
		);
	}
	
	$command = "SELECT * FROM tbl_users";
	
	$result = $dbo->query($command);
	
	if( $result === false )
		throw new PDOException(
			'<pre><h1>Query error:</h1>  ' . $command . ' is NULL.</pre>'
		);
		
	$data = array();
	while($row = $result->fetch(PDO::FETCH_OBJ)) {
		$data[] = $row;
	}
	
	echo '<pre>'; print_r($data); echo '</pre>';