/**
* @param Entity_Tree $elem
* @return bool
*/
public function deleteTree($elem)
{
$rk = $elem->getRightKey();
$lk = $elem->getLeftKey();
$tree = new DAO_Tree();
$res = $tree->getChild($elem->getId());
$this->deleteChildFromTable($res);
$del = $this->DB->prepare('DELETE FROM `site_tree`
WHERE `left_key`>=:left
AND `right_key`<=:right');
$del->bindParam(':left', $lk);
$del->bindParam(':right', $rk);
$q1 = $del->execute();
$del = $this->DB->prepare('UPDATE `site_tree`
SET `right_key`=`right_key`-(:right-:left+1)
WHERE `right_key`>:right AND `left_key`<:left');
$del->bindParam(':left', $lk);
$del->bindParam(':right', $rk);
$del->execute();
$del = $this->DB->prepare('UPDATE `site_tree`
SET `left_key`=`left_key`-(:right-:left+1),
`right_key`=`right_key`-(:right-:left+1)
WHERE `left_key`>:right');
$del->bindParam(':left', $lk);
$del->bindParam(':right', $rk);
$del->execute();
return $q1;
}