Generate Random String from digits and letters with PHP
function generateRandomString($length = 30) {
	    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
	    $charactersLength = strlen($characters);
	    $randomString = '';
	    for ($i = 0; $i < $length; $i++) {
	        $randomString .= $characters[rand(0, $charactersLength - 1)];
	    }
	    return $randomString;
	}