public function bindValue($param, $value, $type = null)
{
if (null === $type) {
$type = 's';
} else {
if (isset(self::$_paramTypeMap[$type])) {
$type = self::$_paramTypeMap[$type];
} else {
throw new MysqliException("Unknown type: '{$type}'");
}
}
$this->_values[$param] = $value;
$this->_bindedValues[$param] =& $this->_values[$param];
$this->types[$param - 1] = $type;
return true;
}