/**
* Select result of a sub-query.
*
* @param Query $sub The query of which to select result.
* @param string $alias The alias to give to the sub-result.
*/
public function selectSub(Query $sub, $alias)
{
$this->addValueToQuery($sub->getValues());
$subSql = new Expression('(' . $sub->getSql() . ')');
$this->_selectColumn($subSql, $alias);
}
