/**
* Retrieve a single object by pkey.
*
* @param int $pk the primary key.
* @param PropelPDO $con the connection to use
* @return Gradeunit
*/
public static function retrieveByPK($pk, PropelPDO $con = null)
{
if (null !== ($obj = GradeunitPeer::getInstanceFromPool((string) $pk))) {
return $obj;
}
if ($con === null) {
$con = Propel::getConnection(GradeunitPeer::DATABASE_NAME, Propel::CONNECTION_READ);
}
$criteria = new Criteria(GradeunitPeer::DATABASE_NAME);
$criteria->add(GradeunitPeer::ID, $pk);
$v = GradeunitPeer::doSelect($criteria, $con);
return !empty($v) > 0 ? $v[0] : null;
}