View source for JTableNested/check

===Source Body===
<source lang="php">
public function check()
{
        $this->parent_id = (int) $this->parent_id;
        if ($this->parent_id > 0) {
                $this->_db->setQuery(
                        'SELECT COUNT(id)' .
                        ' FROM '.$this->_db->nameQuote($this->_tbl).
                        ' WHERE `id` = '.$this->parent_id
                );
                if ($this->_db->loadResult()) {
                        return true;
                } else {
                        if ($error = $this->_db->getErrorMsg()) {
                                $this->setError($error);
                        } else {
                                $this->setError('JError_Invalid_parent_id');
                        }
                }
        } else {
                $this->setError('JError_Invalid_parent_id');
        }

        return false;
}
</source>