##### creating a connection variable in connect.php ####
require_once('/../../../connection_info.php');

$db_host = 'localhost';
$db_user = 'root';
$db_pass = 'somePaSSWoRd';
$db_name = 'database_name';
    try
	{
        $pdo = new PDO('mysql:host=' . $db_host . ';' . 'dbname=' . $db_name . ';' . 'charset=utf8',$db_user,$db_pass);
	}
	catch (PDOException $e)
	{
	echo $e->getMessage();
	}


#### typical use in someFile.php ####

require_once('../connect.php');


function get_book_details($input, $pdo){
	$username= $input['username'];
	$password = $input['password'];

	try{
		$q = $pdo->prepare("SELECT * FROM users WHERE user = :user AND pass = :pass");
		$q->bindValue(":user", $username);
		$q->bindValue(":user", $username);

		$q->execute();
} catch (PDOException $e){
	echo $e->getMessage();
}