function __construct($dbuser = '', $dbpassword = '', $dbname = '', $dbhost = 'localhost', $encoding = '')
{
$this->dbuser = $dbuser;
$this->dbpassword = $dbpassword;
$this->dbname = $dbname;
list($this->dbhost, $this->dbport) = $this->get_host_port($dbhost, 3306);
$this->encoding = $encoding;
}