/**
* Indicates if a previous version of the package is installed.
*
* @return boolean True if a previous version of the package is installed.
*/
public function previousVersionInstalled()
{
$this->parseSignature();
$count = $this->xpdo->getCount('transport.modTransportPackage', array(array("UCASE({$this->xpdo->escape('package_name')}) LIKE UCASE({$this->xpdo->quote($this->identifier)})"), 'installed:IS NOT' => null, 'signature:!=' => $this->get('signature')));
return $count > 0;
}
