public function fetch()
{
/* fetch by current query */
$dsId = $this->getSchema()->getReadSourceId();
$conn = ConnectionManager::getInstance()->getConnection($dsId);
$driver = $conn->createQueryDriver();
$arguments = new ArgumentArray();
$this->_lastSql = $sql = $this->getCurrentReadQuery()->toSql($driver, $arguments);
$this->_vars = $vars = $arguments->toArray();
$this->handle = $conn->prepareAndExecute($sql, $vars);
return Result::success('Updated', array('sql' => $sql));
}